Original subtitles

In 1911, young American explorer Hiram Bingham

arrived in Peru's Sacred Valley.

Bingham was looking for a fabled lost city,

the last redoubt of the Inca

in their doomed battle against the Spanish.

He met a local farmer,

who said he knew of a place which might interest the American...

..a place overgrown and all but forgotten.

What Bingham saw astonished him.

Peeking through centuries of vegetation

were dozens of granite buildings.

Vast terraces were cut into the mountainside,

criss-crossed by hundreds of steep, stone steps.

The effect on the young explorer was dazzling...

like a dream.

When Bingham arrived here at Machu Picchu,

he thought he had discovered the Lost City of the Inca,

a place so secret, it had remained hidden as Europeans overran

the entire continent of South America.

For Bingham, this site was the Holy Grail,

the key to unlocking the mysteries of the Inca,

the largest pre-Columbian empire in the Americas.

But Machu Picchu provides only a glimpse of an incredible empire.

It's only one part of a remarkable tale.

This is the story of a people who, 600 years ago, built an empire

that stretched from barren coastal desert to lush tropical jungle,

from the edge of the Pacific Ocean

to the high plains of Chile and Argentina.

It's a story of wealth, power, innovation and bloodshed,

all happening in some of the toughest landscapes on the planet.

Fundamentally, this is the story of an empire unlike any other,

one with a completely different worldview to the Europeans

who come to conquer it.

And it's that different way of seeing the world,

of gaining and holding power over so many people,

that make the Inca absolutely fascinating.

The question I want to answer is,

how did they do it?

There are very good reasons why the Inca have long fascinated us.

Their empire was the biggest in the Americas

before the arrival of Europeans.

At its height in the 15th century,

over ten million people were under their rule.

Their vast kingdom was connected by a sophisticated road network,

stretching for thousands of kilometres.

But most remarkable of all

is the apparent speed of their rise to power.

In the 14th century, the Inca were one of many independent peoples

who lived high in the Andes.

Yet they emerged from their Cuzco stronghold and,

seemingly in the space of just 150 years,

built a vast multiethnic empire which spanned a continent,

from the Pacific to the Amazon, incorporating huge swathes

of the modern=day countries of Ecuador, Peru, Bolivia,

Chile and Argentina.

For many years, our understanding of the Inca has been dominated

by the chronicles written by the Spanish conquistadors.

But these chronicles are written often with a very specific agenda in mind...

to justify the Spanish Conquest.

The Spanish came across an empire

which they had no frame of reference for...

effectively a Neolithic Empire run without the pen or the sword.

No writing, no wheel,

no animal which could carry a human,

no markets, no currency.

So a whole, peculiar, complex society in European eyes.

I think it's time to question whether we need to re-evaluate

the Inca rise to power.

Perhaps early historical records have been misleading.

Is there a different, far more intriguing, story to be told

about the emergence of the Inca Empire?

The most important thing to bear in mind is that this wasn't an empire

like the British Empire or the Roman Empire,

where histories were carefully written down

and power came in the form of a dozen legions

or the barrel of a gun.

This was a non-Western empire

and that's often made it difficult for westerners to study.

In order to understand the Inca,

you need to get inside the Incan mind, and think like they thought.

And that means getting far away from Machu Picchu.

One of the major differences between the Inca world and our own

is the concept of time.

The Inca thought differently than we do

about the past, present, and future.

And this has significant implications for understanding

all aspects of Inca history,

and not least how long it really took them to build their empire.

The way that we think is so ingrained that it's very hard

to try and change our perspective on things,

but it's something we have to do

if we are to understand the Inca Empire.

We have to get inside the Inca mind.

For us, we have life.

We are born and then we die.

And this is essentially a linear path.

Everything that happens before a moment of our lives

we would call "history" and it happens behind us.

Everything that's going to happen beyond this point in this line,

we would call "the future".

Crucially, therefore,

everything that we understand about our ancestors

and the world that has gone before

creates and affects our lives along this line.

And everything that we do in our own life will affect the future

and this is a linear concept of time.

That is completely different to how the Inca understood time.

So for the Inca, start with the first line,

which they might call Kay Pacha.

Kay Pacha is essentially a lifeline.

But there are two parallel lines, Hanan Pacha and Uku Pacha,

which is the past and the future.

And these lines run in parallel

because they can happen at the same time.

So at any particular moment of life on this line,

they can transect between the past and the future.

And this point here is a particular moment of experience

in the present which is affected directly by the past or the future.

We get a sense that there were multiple histories,

there were multiple pasts

and there were multiple references

to different things that different ancestors had done

depending on who was telling the story.

So, because of this, it becomes very difficult to determine exactly

what was the historical sequence of the development of the Inca Empire

in a way that would make sense to us as a nice European chronicle.

The Inca don't talk the same language of time as we do

and so we need to think about the chronology

of their history quite differently.

By understanding this, we can begin to unravel the true story

of the rise of the Inca Empire.

If you contrast the historical information

to the archaeological information, we get a very different picture.

Studies of the emergence of the Incas as a power

over neighbouring societies surrounding Cuzco

show that they were probably a pretty potent society,

perhaps even a state, as early as almost 100 years before

their emergence as a ruling empire.

This means the origins of the Inca date back much further

than we originally thought.

I think it also means that when they started to build their empire,

the Inca built upon the achievements of people who went before.

A few hours' drive south of Cuzco,

there are the remains of a long-forgotten settlement...

..remnants of buildings and streets

which stretch over nearly two square kilometres.

But these ruins aren't Inca.

They were built by a people who rose and fell

long before the Inca dominated this region.

These people were called the Wari

and this place was known as Pikillacta

and I believe the Inca learnt a great deal

from what the Wari built here.

Throughout this part of South America,

you can find the remains of cultures stretching back thousands of years.

These past societies had their own world views, belief systems

and ways of living their lives.

And it's understanding the inter-relationships between them

that is important.

No society suddenly appears independently on its own.

But some societies can be so successful

that their influence spreads far and wide.

That was the case with the Wari.

The Wari were the first to unite multiple areas,

from north to south, covering most of modern-day Peru.

Pikillacta was one of the Wari Empire's

most impressive settlements.

It's been estimated that, cumulatively, it would have taken

six million days of back-breaking labour to build it.

This is a vast and beautiful site

and a really important one for the Wari.

But it's when you walk around

that you get a sense of experience of the place,

because they had these incredibly long corridors

with these dominating high walls.

It must have been quite a disorienting experience.

Perhaps led through one of these doorways,

you enter out into these open spaces or patios

that would have covered in white paint and perhaps murals.

Pikillacta dominated this region

towards the end of the first millennium.

And walking through these ruins today, it seems to me the Wari

laid the foundations of how to build an empire in the Andes.

Many of the ideas of so-called Inca statecraft which we think of

actually had their roots in the Wari.

Not least the road system.

You can't create a road system in the time period

that the Incas were around in.

There was a great expansion of people and ideas at a time

far deeper than the Inca Empire.

Critical to the success of the Wari

was their understanding of this brutal environment

and the innovations they developed to overcome it.

The Wari were masters of landscape transformation.

Canals that brought the water down from the mountain peaks,

where the rains fall,

into the rich agricultural regions where they terraced the landscape

in order to turn the mountainsides into productive agricultural lands.

The ingenious solutions we see at work at Pikillacta are,

I believe, crucial in helping us to understand

not only the success of the Wari,

but also the Inca who came after them.

This aqueduct is part of a 48km-long network of canal systems

taking water from the high mountains right into the heart of the site

of Pikillacta and down to the agricultural terraces below.

This region receives barely enough water

to support large-scale agriculture or settlement.

And in times of drought, this land can become an incredibly difficult

place for humans to thrive.

90% of the rainfall in the Andes falls on the jungle regions.

Only 10% makes it to the western coasts.

Only through increased efficiency in agricultural technologies

and production can humans respond effectively to drought.

That's what the Wari introduced.

The lesson of the Wari is that

before you can build an empire in this part of the world,

you first need to master the landscape itself.

The Wari agrarian technology was a drought adaptive technology.

It was much more efficient in the use of water

than previous systems had been and that gave the Wari an adaptive edge

in bringing their new system to these local groups

that were living in that region at the time.

Interestingly,

the challenges faced by the Wari still affect people here today.

1,000 years later, Peru's climate remains one of the most extreme

and vulnerable in the world.

Most of the rainfall that falls on the Andes

comes from South Atlantic sources,

coming in as part of the monsoonal system across the Amazon

and brought up into the Andes.

Whereas the western side of the Andes and the coast is a desert,

effectively, because the winds that come across the Pacific are dry.

Most of the population of Peru today live on that desert strip.

I've come to the village of Maras, high in the Andes,

where a dry spell has made life tough for local farmers

like Felicitas Torres.

THEY SPEAK SPANISH

Authorities in Maras have responded to the dry spell

by bussing in containers of fresh water from Cuzco.

It has helped, but it's in no way a sustainable solution.

What's happening in Maras today also happened here many centuries ago.

But the Wari did not have the option

to bus in tanks of water to sustain them.

At the end of the first millennium, we know that conditions

were both dry and really quite cold up in the mountains.

And that's the time when the Wari disappeared

from the archaeological record.

The Wari understood their environment,

but a prolonged drought may have proved too much, even for them.

Climate change could have been one of the factors

which put a lot of pressure on the Wari.

Now, the societies knew how to deal with short-term climate change.

They had in place a lot of strategies

that enabled them to cope.

But climate at those altitudes is one of the real pressure points.

However ingenious the Wari solutions were to the challenges they faced,

their power waned.

But there can be little doubt that the Inca built on the knowledge

of what the Wari left behind.

We have people continuing to live in the Cuzco region,

continuing the oral traditions and the historical traditions

of the Wari within the Cuzco region

that the Inca could have picked up upon.

The Inca also had the benefit of the monuments that the Wari had built,

and right in their back yard.

The Wari created a large and powerful state.

They were able to harness the harsh environments

using ingenious large-scale construction projects like this,

technologies often associated with the Inca.

But the reason I like this one is that you can see the original

Wari construction behind, re-used and restored by the Inca

with this lovely stonework at the front.

The Inca are using Wari technology, but the crucial difference is,

they're also up-scaling it.

To see exactly how they did this, I'm heading north,

into the heart of the Cuzco Valley.

This mountainous land is not naturally suited

to large-scale agricultural production.

The challenges presented by the harsh climate are considerable.

But here, the Incas' remarkable ability to problem solve revolutionised agriculture

and played a key role in the expansion of their empire.

This is Moray.

It lies 3,500 metres above sea level

and is one of the most remarkable human landscapes on earth.

Moray consists of three huge limestone depressions,

into which terraces have been carved.

This is the place where Inca skills in engineering

and agriculture combined perfectly.

It's a place which synthesises beauty and technology

and transformed the lives of the Inca and those they would soon rule.

These terraces can be up to three metres in height

and they have this thick retaining wall

which is angled back to hold back the soil behind.

And what's behind is actually really clever.

At the bottom, you have a series of broken stones for drainage.

Above that, a layer of coarse soil, which acts as a bedding,

and then a metre of topsoil, which they continually turn over

to aerate the soil.

And these stone walls absorb the heat of the sun during the day

and that radiates through at night, protecting the crops against frost.

The ingenuity of the terraces lies not just in their ability

to increase the amount of land the Inca could cultivate.

They were a mechanism for manipulating the environment,

altering the ambient temperature of the whole site...

..and making the production of crops at high altitude possible.

Today, the temperature at the top of the terraces

is 16 degrees centigrade.

Down here at the bottom, you have this crucible effect

where the temperature is much warmer, there's no airflow,

and these stone terraces circle round, radiating the heat.

Here, you can see it's over 22 degrees now.

The difference in temperature from the top of this site to the bottom

means that each terrace at Moray represents a different

ecological zone as you move up the side of the Andes.

The implications of this are profound.

It means this was a place where Inca engineers

created their own micro-climates, allowing them to experiment

in cultivating a variety of different crops

which would not normally have been grown at these altitudes.

Tomatoes, squashes, pumpkins, types of tobacco.

That's not so beneficial, perhaps,

but it underlines the point that, although we marvel at

the Zen aesthetic of Machu Picchu and so forth,

really what's much more important, in my view,

is the legacy of their agriculture.

The Incas were essentially reconfiguring the biotic landscape

by changing the terrain, changing the heat

and water retention capacities through their terracing systems,

which developed a series of warm weather estates

in a cold weather climate.

These terraces show how the Inca understood

the advantages of this vertical landscape.

In effect, they farmed upwards.

They managed to turn the harsh contours of the land

to their advantage.

And by growing different crops at different elevations,

it gave them a huge diversity in the crops that they grew.

This had two key advantages.

One, they had a healthier and more diverse diet.

And two, it helped mitigate against the impact in the past

that had created hunger and unrest...

droughts and floods, pests and frost.

This is what I mean when I say the Inca scaled up Wari technology.

Inca agriculture wasn't just about feeding a family, or even a city.

It was about scientifically managing production,

so they could feed an empire.

By creating this food surplus,

it provided time to devote to other things,

like expansion beyond their borders.

It was also a great calling card as they approached other cultures,

because Moray shows that the Inca were problem-solvers

and able to create these very efficient and effective managed landscapes.

And in a region where climate was unpredictable and catastrophic,

where people could often face starvation and hunger,

the ability to provide a reliable, regular and good quality amount

of food was a source of supreme power for the Inca.

But that's only part of the story.

For the Inca state to flourish, they needed not only to grow enough food,

but also to distribute it quickly and efficiently,

which could be a serious problem

when you live in such a challenging landscape as this.

But a few miles north of Moray

is a place which I think might hold the answer.

This is an amazing spot. Below me is the town of Ollantaytambo.

And above it, clinging to the side of the cliff,

is a series of tall buildings.

At first glance, they may not seem like the most impressive thing,

but these structures are critical to the foundations

of the entire Inca Empire.

These are qollqas, storehouses,

and they are iconic buildings found all over the Inca empire.

Sometimes they are by the side of roads,

sometimes near centres of population,

like here, at Ollantaytambo.

These weren't just barns for storing food.

They were sophisticated silos that were critical

to the well-being of the people and the maintenance of power.

In here would be stored everything from maize to potatoes,

textiles to weapons, and vast numbers of seeds

that could be used for next year's planting.

They were often located in strategic places, well ventilated

and not prone to flooding.

The combined storage space of this network would have run

to hundreds of thousands of cubic metres.

That means that people across the Empire could be supplied

with everything they needed, whenever circumstances demanded.

One of the ways that we can understand the scale and order

of the Inca warehousing system

is by looking at the experience of the Spaniards who came in

in 1548 into the upper Mantaro Valley

in the central highlands of Peru.

There were 2,000 of them and they stayed there for multiple weeks

and they said, at the end of that period,

they couldn't recognise that they'd made a dent in the warehouses

and in the contents of the facilities.

These storehouses tell me that the Inca understood the need

to provide food security for the people they ruled.

It's actually quite a modern idea.

In the UK, during the fuel protests of 2000,

supermarket bosses told the government they only had enough fuel

to distribute food to the people for another three days.

After that, they'd start to go hungry.

This focuses the mind on food security,

because it's not just about growing food, it's about its storage

and distribution that is perhaps the most important.

And the Inca understood this.

That's why they created this vast system of storage facilities

and a distribution network that got the food to the people.

And this was important during times of drought

and environmental disaster.

The Inca storehouses, in times of scarcity and in times of drought,

could be used to feed the populaces, to feed the masses,

in order to save them from certain death and destruction.

To the people who did the farming, they were a source of security.

An insurance, if you will, against the bad years,

knowing that the Inca state would be able to provide for them.

But I suspect these storehouses served more than a practical,

administrative function.

The storehouses provided a highly visible symbol of the Inca state

to its people, demonstrating both its reach and its benevolence.

There was a basic level of understanding that the Inca

would care for the poorest members of its society.

It was a basic social contract, if you will.

These storehouses were an important logistical element

of a growing empire.

But they also hint at the developing nature of Inca power itself.

You get the sense of a different type of empire

when you come to a place like this.

You see how much effort they went to, to provide for people's needs.

It's almost an attractive type of empire

that people would want to become part of.

Why wouldn't you want to join an empire that provided for you

in times of need, good times and bad?

The creation of these storehouses tells us a lot

about the great Inca ability to organise and plan

the use of their resources

They embody an empire which could offer solutions

to the people of the Andes.

But in order to truly understand the nature of Inca power,

I think we also have to look at how they approach

these people in the first place.

How, in effect, they pitched their empire

to the people they would rule.

To find out how they did it,

I'm taking the road west, towards the ocean.

This is the Temple of Pachacamac, on the Pacific Coast of Peru.

And you can see the distinctive method

of Inca empire building at work here.

For thousands of years before the Inca,

this was one of the most important and powerful religious sites

in South America.

Pachacamac's followers came from as far away as Ecuador

and Bolivia to consult the oracle housed here.

This massive complex was nothing less than an American Mecca.

Which perhaps makes Incan attitudes towards Pachacamac

even more surprising.

They didn't destroy this religious centre,

stamp out its idolatry or even forbid people from worshipping

the oracle here at Pachacamac.

Exactly the opposite, in fact.

They incorporated the oracle of Pachacamac

within their own pantheon of deities,

even building a shrine to it in Cuzco.

This willingness to tolerate and absorb other religions

tells us a great deal about Inca power.

It tells me that, as they expanded into new territory,

they wanted to avoid conflict.

The Incas were very effective at expanding out of their homeland

because they practised economy of force.

That is, they didn't conduct military operations

except as a last resort.

They tried diplomacy, they tried bribery, they tried all sorts

of accommodations to bring people into their empire.

Fighting was inefficient.

It meant the loss of their own men

and of the people whose labour they could use.

But the threat of force needed to be visible and real.

It is a carrot and stick approach, if you like,

of the threat of military violence, but equally,

the promise of gaining through the authority of the Inca

and their access to resources.

The Inca would often arrive in a new province with a massive army,

putting on an overwhelming display of force.

Emissaries would be sent to local rulers,

bearing expensive gifts of jewellery and livestock.

These same emissaries would explain the benefits

of joining the Inca Empire.

If the answer was no, the Incas spared no prisoners.

Losing generals could expect to be flayed alive.

But if the answer was yes,

then the people would be showered with gifts of food and drink.

Their lords would be instructed in Quechua, the Inca language,

and their children would be taken to Cuzco

to learn the ways of the Empire.

Above all,

they would be allowed to continue to practise their own religion.

Pachacamac is an excellent example of how the Inca

co-opted a powerful religious shrine and incorporated it

into the Inca imperial period.

They probably persuaded the priests of Pachacamac to participate,

those that would be willing.

But they also transformed, then, Pachacamac

from its focus as a local shrine into an Inca one.

And that kind of melding and that kind of blending, if you will,

of Inca ideology with local ideology was a really good example

of the way that Inca imperialism worked.

The tolerance demonstrated here at Pachacamac

happened all over the Inca realm.

And I think it goes to the heart of explaining

how the Inca built such a large empire.

If you submit to the rule of the Inca Empire,

then you will be allowed to keep most of your lands,

you'll be able to keep your social order.

All you will have to do is to pay certain taxes to the Incas

and we will allow you to continue to live essentially

as you had done previously.

It appears that many peoples in the Andes decided

that was probably the best bet.

There's a great intelligence about Inca power.

Why destroy a kingdom when that will mean a heavy cost

to you in terms of lives lost?

Why persecute its rulers when they could help you run your empire?

Ultimately, the Inca understood the more tightly you bound people

to you, the more control over them you would have.

In order to develop a larger-scale society,

they needed to cooperate.

And that's one of the great Inca achievements,

is that level of cooperation.

Now, it wasn't all love and peace, I think, but nonetheless,

it wasn't aggression that developed into the defence of sites

and all-out warfare.

And I think that allowed them to expand, as they created more and

more alliances and they could draw people together.

In doing so, they are creating an integration

that is different to what has gone before.

By the late 1400s, the Inca Empire was approaching its zenith.

The Inca were no longer one among many societies in the Andes,

they were the dominant, highly organised culture whose influence

stretched well beyond their Cuzco stronghold.

But in economic terms, how did such a sprawling empire work?

To find out, I'm heading to the remote island of Taquile,

4,000 metres above sea level on Lake Titicaca.

The people on Taquile live by an old code,

which they say dates back to the Inca,

"Ama sua, ama llulla, ama qhilla."

"Do not steal, do not lie, do not be lazy."

These lands were among the first the Inca conquered

as they moved out of the Cuzco Valley.

It's a region of vast llama and alpaca herds,

which were a bountiful source of food, clothing and transport

for the Inca.

And the Incan way of life is still very much in evidence

here on Taquile.

An attitude of collective endeavour and mutual support.

Ola.

'Alejandro Flores Huatta is a community leader.'

Alejandro's way of life may seem anachronistic,

but at the time of the Inca, this was the norm.

Communities were expected to give a proportion

of their agricultural production, crafts and labour

for the benefit of the state,

weaving cloth for the court or working on a building project,

just as they still do on Taquile today.

One of the clearest examples of a difference between

the Inca way of life and the modern one is in the economy.

Because the Inca didn't use money,

they didn't have an arbitrary system against which value was set.

Instead, everything was done through exchange.

So things like agricultural produce and craftsmanship,

even hours of labour, could be exchanged.

The Inca managed to persuade large numbers of people

that they should contribute their labour to projects

such as construction, such as agricultural work,

such as the road system.

And they managed to do that through a reciprocal relationship,

one where you didn't doubt that the Inca were in control,

but that you believed that you were getting also something out of it.

It strikes me that, in stark contrast to many civilisations

that had gone before them, the Inca wielded a very subtle form of power.

They offered solutions to the harsh realities of life in the Andes

and, in turn, asked the peoples they governed to have faith

in the benefits of Inca rule.

It some ways, it was quite a benevolent empire.

Yet there was never any question about who was ultimately in charge.

How the Inca managed to integrate so many different peoples

into their empire whilst maintaining their dominant position

was central to their success.

Just a few miles from Pachacamac is a place which was built specifically

to bring an entire people into the Inca fold

and it brilliantly demonstrates how a society

that didn't have any written culture

still had ways to ensure that everyone knew their place.

This is the site of Tambo Colorado.

It's one of the first settlements the Inca build

as they push westwards, down towards the Pacific Coast.

The people who lived in this region were the Chincha.

And the purpose of this place was to co-opt them into the empire.

The Chincha were one of the Incas' most important allies,

controlling large swathes of the coastal desert.

And it's obvious that this was an important place for both

the Chincha and the Inca,

dominating a flat plain as the mountains give way to the coast.

'Sofia Chacaltana Cortez is an archaeologist

'who has studied this site extensively.'

So this entrance, like, the whole wall comes along

and then you've just got one small entrance into the site?

Yeah, that's typical of Inca architecture, right?

Like, it's an entrance that is a palace first

and it has just one entrance and also has the Inca shape,

the trapezoid, so...

Wow, and then you immediately come into this sort of main plaza.

Yeah, you have the main plaza.

This one is the rear plaza and then you have three other plazas.

So what sort of activities would be going on

in this sort of main plaza, do you think?

If people walked through those gates,

what sort of things would they see?

Well, probably ritual activities and also a lot of drinking.

The Inca did a lot of drinking and displaying of power.

But probably also that was the place where the elite could come,

could enter the site.

Tambo Colorado has the feel of a stage,

a place of performance,

where important officials would meet, where religious rituals

would take place, against the backdrop of feasting and drinking.

Adding to this theatrical feel are these brightly painted walls,

whose colours have survived over five centuries of desert sun.

It's absolutely extraordinary that you get this level of preservation

of these pigments and paints right up to the modern day.

I really like the idea that you sort of walk in

from this quite barren desert landscape

and then when you walk into this plaza,

suddenly you're, like, overwhelmed by the colour.

Like, brilliant colours around you

and then you can think about that dancing and music which is going on.

Much of what we see at Tambo Colorado

is typical of Inca architecture.

Yet there are striking differences in the craftsmanship here, too,

which Sofia believes come from the influence of the Chincha.

Something to notice, too, is the lattice work

and the ending of the Inca spaces are not always Inca, are Chincha.

The architect probably was Inca but the work was local

and also probably the people that were living here

were the Inca elite and the Chincha elite.

It's a really difficult thing to assess,

but do you think there's any evidence that

the Chincha and Inca are working cooperatively,

rather than sort of like a dominating workforce, forcing them,

do you see any evidence of collaboration?

Well, we are seeing here is like, I think,

the synthesis of the government.

Like, after they have, like, worked together.

I think this is like a...

probably like a Chincha... an Inca-Chincha palace, right?

It's not only Inca, it's not Chincha,

it's saying, like, "We are cooperating."

The merging of architectural styles

signals the joining of two kingdoms, Inca and Chincha.

Tambo Colorado was the place which marked an important alliance

in material form, but not an alliance of equals...

..because there are subtle levers of control here.

Away from the plazas,

Tambo Colorado is a maze of complex and confusing corridors.

Hidden rooms and secret spaces.

The architecture dictates how you travel around the site.

Even the beautiful, brightly coloured walls

had a controlling purpose,

marking out areas of access according to rank.

The yellow colour is representing the higher status.

The lower status will be the white,

that will represent the intermediate elite

and the red will represent the locals.

The colour scheme was designed to mark places

where only the Inca were allowed.

A lot of Tambo Colorado would have been off limits

to the Chincha population.

So these corridors are fantastic.

They have this sort of real sense of restricted space. Yes.

And they go to imperial spaces.

We will see these Inca spaces, like the font, the Inca font,

and there is an Inca way of purifying your body.

To what extent do you think these architectural forms,

these spaces, are a mechanism for the Inca Empire to sort of control

people's behaviour and influence their experience

of coming into them?

Well, I think this is to control people's behaviour

and also to show how to behave as an Inca, right?

Because we are far away from the...

from the capital.

So I think also is showing what is the Inca behaviour, right?

To behave as an Inca, I think, was an important part

of the Inca government.

I think it's cooperation also,

but with the foot on top, kind of like that.

It's great chatting to Sofia

about how Inca architecture controls people's behaviour here.

And more than that,

communicates it to all the people moving up and down this valley.

Inca architecture is so much more

than the construction of imposing buildings.

Architecture, like religion or agriculture,

is a source of Inca power.

All the elements that made Inca power so dominating and seductive

came together in one city...

Cuzco, high in the Andes.

Cuzco was the most important city in the entirety of the Americas.

It was the Inca homeland

and the political and spiritual heart of their empire.

And in the heart of Cuzco sat one person...

the Sapa Inca.

The ruler of the Inca Empire

was a person called the Sapa Inca or Unique Lord.

He embodied all the dimensions of leadership within the Inca society.

He was the political ruler, in part because he was the descendant

of the previous Sapa Inca.

He was also the military leader

and he was the person who made decisions about everything

that was of significance in society,

whether economic, ritual, or whatever.

It was all focused on a single individual.

The Sapa Inca was the most powerful man in the empire

and was treated with immense reverence.

He communicated via intermediaries.

No-one dared look him directly in the eye.

Disobedience was punishable by death.

I guess you could probably call him a benevolent dictator in some ways.

The Sapa Inca was not a very accessible personage,

but he was also expected to be a charismatic leader,

a figure who could change the world when necessary.

The greatest of all Inca emperors was Pachacuti,

whose name literally means "he who overturns space and time".

Pachacuti is a mythical hero to many modern day Peruvians.

The story goes that he was a prince,

living here in Cuzco in the early to mid-15th century,

when the city was attacked by the Chanka,

a people who came from 150km to the west.

Pachakuti's father, the ruler, took his entire court and fled the city,

but Pachacuti defiantly remained and led a divinely inspired resistance

to the Chanka, crushing them.

He then led a series of Inca expansions away from the homeland,

laying the foundations of the Inca Empire.

But the root of Pachacuti's rule and the authority of all the Sapa Incas

lay in their position as semi-divine figures.

To understand how the Sapa Inca operated,

we have to think of him in several dimensions.

He was, in some senses, very much a human being,

but the Incas considered him to be the descendant of Inti,

the Sun God, so in Inca ideology, he was a deity on Earth.

While the Inca allowed their subjects to worship their own gods,

they would always be subservient to their own Sun God, Inti.

The Inca built temples of the sun wherever they conquered.

This emphasised the emperor's connection

to the most powerful god in the sky.

It also connected Inca power with the cosmos itself.

In this way, the Inca used religious reverence

as a powerful political tool.

Inca religion is probably best thought of as part

of an over-arching imperial ideology.

It had its political elements, it had its religious elements,

it had its practice, it had its military and cosmological elements.

So the idea of religion, per se,

probably would not have made sense to the Incas.

They would have thought of it as an integrated part

of the sanctity of the ruler, of his legitimacy to civilise the Andes,

of his role as a political and military figure.

Here, at the temple of Qorikancha, the holiest spot in the empire,

the Sapa Inca would hold court.

This entire complex would once have been encased in gold.

All that remains today is this beautiful curved stone wall.

But despite its destruction

and the construction of a Christian church on top of it,

the Qorikancha still feels very much like

the spiritual heart of Inca Cuzco.

The Qorikancha was at the centre of the Inca world.

It was thought that, from here, dozens of ceques, or ley lines,

spread across the empire, upon which shrines and temples would be built.

So this religious complex was connected physically

and psychologically with every corner of the empire.

The Inca used religion to project the idea of their empire

over the lands they controlled and to the people they ruled.

These ley lines radiated across the landscape,

creating a spiritual map of the empire

which would have been understood by people from the forests of Ecuador

to the high plateaux and peaks of the Andes,

and from Cuzco to the coast.

You have to picture this as a countryside which is animated,

it's alive with different special places,

places which are associated with supernatural powers.

And so an unusual rock, a pass,

a curve in a road, a waterfall...

..any noteworthy landmark on the landscape could be considered

what the Incas called a huaca, or a shrine.

And on very specific days of the year, pilgrimages would be made.

Different kin groups would line up along different lines

and march out to each of the shrines, making offerings to them.

For the Inca,

this was an empire of the mind as much as a physical empire,

held together by thousands of shrines and invisible ley lines

as much as by garrisons or military power.

But an empire still needs physical bonds.

By the end of the 15th century,

the Inca Empire was approaching its greatest extent,

reaching from southern Ecuador eastwards to Bolivia

and into northern Argentina.

It was criss-crossed by 40,000km of roads.

There were two main roads,

one running from Cuzco to Quito,

the other running parallel along the coast.

Between these were dozens of connecting roads and spurs,

heading south and east.

This road system is one of the most famous elements of the Inca Empire.

But much of this network almost certainly predates the Inca.

Once again, they took what they found and up-scaled it.

Some parts of that road system

existed at least since the Wari Empire,

but the Inca develop it.

They reconstruct large parts of it.

They construct bridges and causeways to integrate it

and they redirect some roads.

This is a huge investment for them.

The Inca road system was a triumph of architecture and planning.

The roads had to pass through a variety of landscapes,

from arid desert, to snowy mountains, to vertical cliffs.

They could be anything from one to ten metres wide.

In the desert, they were protected from dusty winds by raised stones.

In the mountains, they were designed to allow for run-off and drainage.

And when the terrain made conventional roads impossible,

the Inca once again came up with an ingenious solution.

This is the stunning Keshwa Chaca bridge.

It's made out of only this, straw.

And it's been in use for hundreds of years,

dating right back to the Inca period.

This bridge still serves as a major crossing of the Apurimac River.

It is carefully maintained by the four communities who live here.

Ola.

'Among the workers is Dante Quispe Locuber.'

The roads allowed the Inca to travel swiftly and communicate efficiently

throughout their vast empire.

It's estimated a message could be carried from Cuzco to Quito,

a distance of 1,500km, in just five days.

But seeing Dante and his comrades at work, it strikes me that the roads

were about much more than just communication,

more than just getting from A to B.

This network was a psychological tool,

as well as a physical one.

These roads and bridges were a constant reminder to communities

all over the Andes that they were part of something bigger.

It probably provided an ideological mechanism of integration,

so that in constructing that road system,

you could not but be aware that you were integrating Cuzco with the coast.

You were a part of empire.

We must remember that there is no idea of a map of the Inca Empire.

It is largely through the connection of individual places,

through roads and track ways and though ceremonial

and ritual activities that the Inca Empire holds together.

The network was so vast

that new parts of it are still being uncovered today.

This is a newly discovered road.

It's absolutely extraordinary, it clings to the side of the cliff

with a 300 metre drop-off down to the river below.

These roads are about more than just travel.

They are the physical ties that bind the empire together

and underpin Inca power.

Armies, food and livestock can move quickly along them.

No matter where you are in the empire,

you're never far from a road that leads to Cuzco.

And that proximity means Inca power is ever-present,

no matter which corner of the empire you're in.

This road leads down to Machu Picchu.

It isn't on any of the tourist itineraries

and it may not be as celebrated as what lies below.

But it is part of the same empire, built by the same people

and is, in its own way, just as important as that iconic Inca ruin.

From a western perspective, ancient empires are lauded

for victorious battles, ingenious systems of governance and control,

territorial expansion and domination through generations.

The Inca achieved all this and more.

If we define power as the ability

to control people's actions and behaviour,

then I think we have a tremendous amount to learn from the Inca,

because force was just one small tool in their armoury.

To give people the sense of freewill,

to make the decisions that you want them to make -

that is the source of true power.

And the scale at which the Inca did it was extraordinary.

But as the Inca reached their zenith,

they would be visited by foreign soldiers from across the ocean.

These Spanish conquistadors had a very different concept of power.

And their determination to build an empire of their own in this land

would lead to a catastrophic clash

of two completely different cultures.