Original subtitles

Central China

and an iconic ancient treasure.

The Terracotta Warriors.

Detail is just unbelievable.

They take your breath away.

An entire army, over 2,000 years old,

stands in formation, ready for battle.

But why?

For decades, archaeologists have been unearthing

a vast, mysterious site that surrounds them.

But much remains unexcavated and undiscovered.

Can technology help to reveal its secrets?

That's the real reason that we're here.

To explore one of the world's

greatest ancient mysteries from above.

I'm Sam Willis, an archaeologist

and expert in ancient civilizations,

and I'm going to investigate China's distant past

from a whole new perspective.

Today, state-of-the-art satellites

and specialized drones can reveal the earth

in stunning detail

and detect hidden archaeology,

enabling us to recreate lost ancient worlds,

invisible to the naked eye.

Working alongside leading Chinese experts,

my team and I will travel to some of the country's

most remote and incredible landscapes.

And with cutting-edge science,

investigate previously unknown cultures,

lost cities and enduring legends.

This is ancient China as you've never seen it before.

♪ ♪

In the grass and scrubland close to the Terracotta Army,

there's one feature that stands out above all else.

The Terracotta Army is guarding that.

Because buried beneath

that rather normal-looking hill behind me

is actually one of the world's greatest wonders:

the tomb of the First Emperor.

The First Emperor is one of the most important figures

in all Chinese history.

He started out the 13-year-old ruler of Qin,

one of Seven Warring States.

For 25 years he fought to conquer all the rest,

and by the time he was 38, he'd succeeded,

awarding himself a new title, Qin Shi Huang Di,

the first emperor of a vast land

that would eventually become known as China.

He was the most powerful man on Earth.

More than 2,000 years later,

his tomb, hidden beneath the mound,

is rumored to contain untold treasures.

But it's never been excavated,

and it's so revered that there are no plans to do so.

And the secrets of the tomb itself

seem to be just one part of an even greater mystery.

From space, lines can be seen surrounding the tomb mound

that seem to form the perimeter of a vast mausoleum

three times the size of Beijing's Forbidden City.

But the Terracotta Warriors are way beyond this perimeter,

almost a mile away to the east.

If they're guarding the tomb, why are they so far away

and what else might lie hidden underground?

Now, with my team of experts, historian Douglas Flowe,

archaeologist Janice Li,

and tech team leader Zhang Jianwei,

we'll work with the archaeologists

making discoveries right now across this huge ancient site,

and use the latest laser technology for the first time,

to seek out unseen evidence

that could help to piece this great puzzle together

and reveal the First Emperor's entire mausoleum

as never before.

Hi, guys.

Professor Zhang's tech team are already getting to work.

Is that alright?

OK, then we're ready to take off.

They're using two different drones.

The first uses photogrammetry,

combining hundreds of photographs

into a detailed 3D model of the ground.

The second uses a technology called LiDAR.

Is this all ready to go up, then?

Yes.

LiDAR fires millions of laser pulses

to detect every feature on the surface.

I can't wait to see what they pick up.

Together, they'll form the most detailed picture ever

of the emperor's mysterious creation.

The team is starting with the feature at the heart of it all:

the burial mound that contains the First Emperor's tomb.

It's going to be quite some challenge.

Not only is the mound enormous, but it's also covered in trees.

And what we're going to do is use this new LiDAR drone

to do something very special.

Hopefully, it will allow us to strip away the trees

and see the surface of the ground itself.

It's never been done before,

so the results could be truly groundbreaking.

According to an ancient text, trees were planted

over the tomb mound right after it was built,

so that it resembled a natural hill.

And what this means is that if our LiDAR works,

we will be the first people in more than 2,000 years

to see every detail of this remarkable construction

laid bare.

After hundreds of images and millions of data points...

- Hi, guys. - Hello.

How you doing?

We're ready to check out the scans of the tomb

with mausoleum archaeologist Shao Wenbin.

This one is the photogrammetry model.

Right.

So the whole area of the mound.

Wow!

It looks like a hill, but if we make it vertical.

The photogrammetry highlights

the distinctive square of the mound.

The tomb mound we're seeing now,

this square shape, is typical of all tomb mounds

belonging to the kings of Qin.

But could the LiDAR scan reveal more?

I got something even cooler to show you.

Alright. Look at that!

This was taken by the drone LiDAR.

It looks similar, but we can eliminate the trees.

By isolating only those laser points

that made it through the thick forest cover,

we can do something that's never been done before:

reveal the surface of the tomb mound itself.

Wow!

That's amazing.

This is extraordinary.

You can see the mound in incredible detail.

So we can see that the ridges going up to the peak,

so it's like a pyramid.

Yes. It's a pyramid with a flat top.

I'm never going to call it a hill ever again.

That's no hill.

We're seeing this giant manmade pyramid, without trees,

for the first time since it was built over 2,000 years ago.

Even after two millennia of erosion,

it still stands more than 160 feet tall,

making it the biggest tomb of a known individual

anywhere on the planet.

And then, in the data, there's something intriguing.

There seems to be some lines here.

Revealed on the surface for the very first time,

something manmade seems to be breaking through

the ground itself in a perfect square.

But what could it be?

Okay, now this area is where we were just watching.

On the surface of a huge pyramid

concealing the tomb of the First Emperor of China,

we're investigating a mysterious manmade feature

revealed by LiDAR.

Here seems higher than this place, right?

Yeah, yeah.

Could this be something to do

with the emperor's hidden tomb itself?

Well, there's a clue we could be onto something.

20 years ago, archaeologists surveyed the mound

using remote sensing.

And using their models, we created this graphic.

The data suggests that hidden beneath the surface,

the emperor's tomb featured thick, terraced earth walls

100 feet high,

surrounding a void the size of a soccer pitch,

with large entrance ramps

descending to a burial chamber deep beneath.

Now our LiDAR reveals something amazing.

This potential structure lines up perfectly

with our mystery feature.

It seems that after 2,000 years of erosion

we could be seeing the top of the First Emperor's tomb

emerging from the earth for the first time ever!

So, we have an idea of the tomb's structure.

The challenge now is just what could lie hidden deep inside?

Fortunately there's a clue, because that same ancient text

that described the tree-covered surface

also gives details of the tomb's interior.

Around a century after the death of the First Emperor,

a man named Sima Qian wrote this.

It's an epic narrative history

called the Records of the Grand Historian.

Or in Chinese, simply as the Shiji.

In it, he writes, "Craftsmen were ordered to make crossbows

and arrows primed to shoot at anyone who enters the tomb."

"Quicksilver," that's mercury, "was used to simulate rivers,

and set to flow mechanically.

Above were representations of the heavenly constellations,

below, features of the land."

Booby traps, heavenly constellations,

rivers of mercury.

It certainly sounds a little farfetched, but not impossible.

To check out the first of these elaborate claims,

our archaeologist and weapons expert, Janice Li,

is in the mausoleum storerooms.

Wow, that's good.

Could crossbows really have been set as booby traps?

The answer might lie with small pieces of bronze

found among the Terracotta Warriors.

This is a replica of the crossbow,

but the bronze trigger is original.

The creation of the crossbow trigger is revolutionary

in military history.

Crossbows were invented in China 2,500 years ago,

and under Qin Shi Huang, they really came into their own.

These triggers make these crossbows

better than longbows.

They can release heavy arrows

from 100 meters to 200 meters.

And also can reload arrows repeatedly.

These weapons played a major role

in the First Emperor's success,

and more than 200 triggers have been found at the mausoleum.

It all suggests the Grand Historian, Sima Qian,

could have been right about the crossbow booby traps.

So, what about the next of his claims?

The heavenly constellations said to decorate the ceiling

of the emperor's tomb.

I've been given a lead to something buried deep beneath

the nearby modern metropolis of Xi'an.

A clue hidden in the most unlikely of places.

This place is great; it's a school, it's a playground.

And just seconds ago it was alive with kids,

but they just all vanished.

This modern campus doesn't look like the kind of place

you'd find answers to an ancient mystery,

but during its construction,

something amazing was discovered here,

and I've been given special permission to explore it.

These tunnels, built to access it, lead deep underground.

I'm here to investigate the Grand Historian's claims

about heavenly constellations

on the ceiling of the Qin emperor's tomb.

Now, many people have written about this

in terms of beautiful jewelry, pearls and diamonds

up on the ceiling.

But that's not what the Grand Historian says.

He talks only of constellations.

So what's the truth?

I'm hoping this place might hold clues.

Oh, look at this!

Oh, it's unbelievable.

It's all over the walls and the ceiling.

What a magical place.

This is the kind of room where your five senses are not enough.

You have to let your mind open and your soul breathe it all in.

This incredibly preserved tomb has been dated to 47 BCE,

only around 160 years after the First Emperor's death.

The colors are so vibrant.

People and animals, swirling patterns.

And the more the more you see, the more you find.

But what can these images tell us

about the tomb of the First Emperor?

Now, this looks interesting here.

Very distinctive Chinese dragon.

This is on the right as you walk in.

If we imagine that is the east,

and that means that somewhere around here...

Yes, here.

The remains of a tiger.

This is my favorite, the white tiger of the west.

You can just see the remains of the distinctive stripes.

In ancient Chinese mythology, on the very first morning,

so just after the beginning of the beginning,

heaven and earth were formed.

And then the constellations appeared,

and each section of the sky was guarded by a sacred animal.

And there may even-- yes, up here, we've got a sun.

So, a black bird, this looks a bit like a crow,

has long been associated with the sun

in Chinese cosmology.

And then that must mean...

Here, we've got the moon

with a distinctive hare and a toad.

And all around us, these are all constellations.

So this isn't just a few images of stars,

this is the entirety of the heavens,

mapped above whoever was buried here, sleeping forever.

This amazing imagery shows just how important the stars were

to the ancient Chinese.

They looked up there for strength, for power,

for security, and for safety.

Because the one thing you could rely on is the sun rising,

the sun setting,

and the stars moving around you above your head.

So, although this tomb is all about

the inevitability of death,

it's also to do with the certainty,

the absolute conviction that there will be a new tomorrow,

that there'll be another day.

As amazing as this is,

it wasn't even for a member of the nobility.

So just imagine the First Emperor's tomb.

Maybe his ceiling also had diamonds or pearls,

but for me, this is a glimpse of its true richness.

The real treasure would have been

these beautiful, intricate images,

and each one with its own power and meaning.

So, crossbow booby traps and a ceiling of stars

both seem to check out.

But what of the claim that seems to me most outlandish?

Inside the emperor's tomb,

were there really China's rivers and seas,

made of mercury?

140 miles south of the Qin Mausoleum,

we're heading to investigate a region that could hold clues

to the rivers of mercury said to flow

through the First Emperor's burial chamber.

For our historian, Douglas Flowe,

it means climbing high into the Xunyang Mountains.

It's really steep up here,

and every once in a while,

you can see a pile of rocks and stones on the road

that has fallen off of the mountainside.

Whoa!

That's pretty close.

Mercury is made by refining an ore called cinnabar.

The question is, was there a good source of it nearby?

And if so, did ancient people have the knowledge

and technology to refine it?

Or even to get to it?

Local expert Guan Zhengbing has been scouring these cliff faces

for years in search of clues.

Watch out, this is really treacherous.

Oh!

It's tough going,

but then, an opening.

This is quite a big cave.

Wow.

Shall we go in?

The cave stretches deep into the rock.

It's pretty eerie in here.

And everywhere, signs that it didn't form naturally.

Look at the traces.

Those are wooden supports left by ancient people.

And look at this.

They've chiseled these grooves here.

Guan Zhengbing believes

these are no ordinary tunnels.

They're mines, and they're seriously old.

Based on our geological research,

this site was in use over 2,000 years ago.

Wow, that's amazing.

That places this mine in exactly the right period,

and Zhengbing has spotted something else.

Look here, do you see the slightly red color?

That is chicken blood stone.

What Zhengbing calls chicken blood stone

we know as cinnabar, the raw material for making mercury.

I see it, yeah, there's a lot of it here.

And down here, it's everywhere.

There's a huge vein of it right there.

So how did they do it?

How did they get the cinnabar off the walls of the caves here?

They would heat the rock with fire,

and cool it with water.

And they would use an iron chisel to break the rock.

This heating and cooling would cause the rock

to crack, giving up its precious cinnabar.

Look at the burn marks.

But could they really have made enough mercury

for the emperor's tomb?

What do you think about the idea that they would have somehow

mined, refined, and then transported enough mercury

that they would be able to create these representations

of rivers at the mausoleum?

Does that sound feasible?

This is entirely possible.

There were probably more than 2,000 caves like this

distributed across this place in ancient times.

It seems this area was a major mercury factory.

And if people were coming all the way up here to get it,

well, it was a highly prized substance indeed.

So, mercury was mined and refined,

seemingly on an almost industrial scale.

And soil samples from the burial mound

also show unusually high mercury levels.

So the evidence backs up the rivers of quicksilver.

The seemingly fanciful tales of the emperor's tomb

might actually be true,

and our LiDAR scans have verified its likely structure.

But the tomb is just the start.

There's still a big mystery here.

Why is the Terracotta Army so far away?

We need to find out what lies between the two

and what else is out there.

Archaeologists right across the emperor's mausoleum

are gradually unearthing the secrets

of his vast construction.

One thing we do know is that he isn't the only one buried here.

To the west, outside the perimeter,

Chinese archaeologists have discovered further tombs.

And Janice is heading to check out one

that's just been excavated.

At over 50 feet deep and more than 300 feet long,

it's the biggest tomb so far unearthed here.

And within it,

lead archaeologist Jiang Wenxiao and his team

have discovered exquisite treasures.

Wow!

The sculpture is so lifelike.

So, these little things

are burial objects.

They are made specifically for that purpose.

It's quite heavy, because it is gold.

This is so exciting.

It's really detailed, you can see the fur,

the hooves here,

and you can see the head, so, it's so detailed.

So happy to have this camel in my hand.

The golden camel is just one of hundreds of treasures

discovered inside this tomb.

Wow, have a look at this.

It's beautiful.

This a dancing figure.

This is so vivid and give a sense of moving, dancing.

Nothing like this has been found

with the Terracotta Warriors, nothing dynamic like this.

Sure. Yes. This indicates the social class

of the tomb owner was high.

All they know so far is that the tomb owner was male

and possibly a member of the royal family.

And this is just one of nine large tombs

known to be hidden here,

while still more smaller tombs and burials

are located all around the site.

Every new find reveals this place is far more complex

than once imagined.

And here, at one of the busiest archaeological sites

on the planet, the discoveries keep on coming.

From terracotta acrobats

and intricate bronze birds,

to ritual stone armor

and chariots,

just like those the emperor would have used in life.

Plotting these onto our 3D model reveals how each treasure

was seemingly placed in a distinct location,

according to a carefully laid out plan.

And these amazing wonders were discovered across an area

way beyond what appeared to be the mausoleum's perimeter,

across an extraordinary 23 square miles;

an area the size of Manhattan Island.

So, why are all these treasures and burials

spread across such a vast area?

I'm hoping another discovery in the east of the mausoleum

might hold clues.

Archaeologists have been excavating here

for the past two years,

and they're unearthing something massive.

Our tech team is preparing to scan it,

this time combining their drones with ground LiDAR.

And it's starting to work automatically.

Let's go.

While they get to work, I want to find out more

from lead archaeologist Fu Jian.

Hello! How are you doing?

Let me show you down there.

He thinks this is a key feature of the mausoleum.

This is the ruin of the east gate.

Once open, it is a doorway which leads to the center

of the Qin Shi Huang Mausoleum.

Let's look at the construction on both sides of the inner gate.

Here's an example.

There is a complete circle of pillar foundations

around the building.

This is the hole for the pillar foundation.

It is about 70 centimeters deep,

so the pillar would have been about eight meters high.

Eight meters tall?

Yes. Wow!

With pillars eight meters, or 26 feet high,

this is not just any gateway.

So just how big was it? And what did it look like?

We want to scan every detail

so we can try to rebuild the gate

as it might have looked 2,000 years ago.

Right, guys? What have we got?

Can you see the gateway?

Look at that.

This is the doorway stone pillar.

And this is a cornerstone pillar.

The distance between the two is the width of the gate.

The scans show the gate would have been huge,

almost 30 feet wide.

It indicates that the structure of this building

is probably quite grand.

Then there are the pillar foundations,

probably where the overhanging eaves were.

This kind of structure is also one of the earliest of this type

ever discovered.

Based on the measurements,

we can do the conceptional reconstruction

of this structure.

From our scans and with the help of Fu Jian

and historical records,

we can rebuild the gate from the ground up.

It reveals a grand gateway, flanked by two-story towers,

bigger than any city gate yet discovered from the same period.

And either side of it,

huge walls stretching right around the mausoleum

with a further inner wall and gateways on every side.

I'd always assumed everything here

was buried or hidden by trees.

But these immense above-ground structures

mean we need to start thinking about this place

in an entirely new way.

This isn't just about a tomb and some pits full of artifacts

and warriors to protect them all.

It isn't just about a burial.

It's far more than that.

The layout, with inner and outer walls,

follows the typical plan of a Chinese city.

And that might explain why the Terracotta Warriors

are located where they are.

It seems they're standing guard close to the main entrance

to an entire city built to serve the emperor in death.

The question is why?

To really understand what's going on here,

we need to get inside the head of the emperor himself.

Douglas is 400 miles south of the Qin Mausoleum,

on the trail of clues that might give us an insight

into the mind of the First Emperor.

Oh, man. Look at this place.

This is the ancient town of Liye.

All of this is clearly very old, but people have lived here

far longer than any of these buildings have been here.

The town itself goes back well over 2,000 years.

It's pretty amazing.

The town of Liye alone is an historic treasure.

But for two millennia, it also kept an incredible secret.

Liye was established by the Chu,

one of the last Warring States to fall to Qin Shi Huang.

It became part of his vast new empire.

And I've heard about an amazing discovery here

that holds clues to the First Emperor's rule

and a glimpse into exactly what he was thinking

2,000 years ago.

This is really exciting.

I've been given special access here.

This precious treasure trove, kept under lock and key,

is something that very few people ever get to see up close.

Hi, nice to see you.

Long Jingsha has been guardian of Liye's treasures

since he discovered them just over 20 years ago.

What are we looking at here?

Here, take a look.

This sliver of bamboo bears writing.

Wow.

Known as a bamboo slip,

it's from the time of the First Emperor

and was found discarded

at the bottom of an ancient well,

sealed in mud that kept it in pristine condition.

I can't believe I'm holding this in my hand,

like you can actually see the writing so clearly,

it's well preserved, and it's 2,000 years old.

That's amazing, look at that.

In all, 37,000 slips were found;

official records and communications

that detail every beat

of the First Emperor's meticulous bureaucracy.

But there's one in particular that Jingsha wants me to see...

Have a look.

...that hints at a personal obsession

of the emperor.

It says in Du Xiang,

the civilians don't have good medicine or good herbs.

What the slip is telling us is that the royal court wanted them

to find some sort of plants as medicine.

And this is how they replied when they couldn't find any.

Oh, so they came back empty-handed.

Do we have any idea what they were actually looking for?

There was a tale that Qin Shi Huang

was looking for medicine to become immortal.

So the First Emperor was searching

for an elixir of eternal life.

He's said to have proclaimed his dynasty would last

for 10,000 generations,

but this suggests something more.

Judging from what I've just seen here in the Liye slips,

it wasn't just his dynasty that he wanted to last that long;

he wanted to be around to oversee it.

This throws up a mystery of its own.

Everything about the First Emperor

seems to be a paradox.

Why does a man so fixated on living forever

spend so much time and resources

on building one of the greatest tomb complexes on Earth?

And that complex,

yes, it's a place of burial, but it's also got high walls.

It's got gates. It's like a city.

What is going on here?

Is this a place of death or is it a place of life?

Archaeologists here might have discovered some clues,

and they've directed our tech team to scan an area

in the northwest of the mausoleum.

Using our LiDAR to strip away the trees

reveals several straight lines and raised areas

that can only be signs of more manmade structures.

To work out what they are,

we need to check them out on the ground.

I'm heading to explore signs of manmade structures

to the northwest of the emperor's tomb

with the mausoleum's lead archaeologist, Shao Wenbin.

Take a look over here.

This row of pebbles is a kind of gutter for a building.

They placed these pebbles

around the sides of the structure.

They were used to stop water causing damage to the ground.

This indicates that there was a building here.

From a distance, this whole area looked quite natural.

But the closer you get, the more you realize

that it's actually very distinctively manmade.

Here you can see the rammed earth ruins

of this building, layer by layer.

These were the foundations of big civil buildings,

built on top of the rammed earth.

Shao Wenbin believes this wasn't just

a few isolated buildings.

This is where we are now, right here.

This whole area is at the northwest corner

of the inner city.

So we're talking about this whole area

was full of buildings?

Yeah.

These structures look very different

from the tombs and gates.

And by combining our scans with historical records

and Chinese archaeology,

we can rebuild them as they might once have looked.

The entire area was covered in palaces,

the biggest and most lavish at the site of our foundations,

close to the tomb mound.

And Chinese archaeologists believe

these were not empty shrines but living, working buildings,

where his subjects continued to serve the dead emperor,

just as they had done in life.

And that changes everything.

It means this isn't just a place of remembrance.

It's built to allow the emperor's spirit

to continue to interact with the living.

At first, this whole site is bewildering.

But what I've learned is that to understand it,

you have to think like the ancient Chinese.

And once you've made that leap of faith,

then everything starts to make a little bit more sense.

The mausoleum is the embodiment of the ancient Chinese concept

of honoring the dead

almost as if they were still alive.

And in the absence of an elixir,

this place is how he would achieve immortality.

Here, even in death,

the First Emperor could remain the great presiding ancestor,

continuing to exert power and influence

on the world of the living.

With this last piece of the puzzle,

I feel like I finally understand the First Emperor

and his mausoleum.

In uniting the Warring States,

he'd achieved something almost miraculous.

And this place was about ensuring that empire survived

long after he was gone.

It's a great paradox that the First Emperor's Qin Dynasty

was the shortest of all of China's ruling dynasties.

But he did leave a legacy like no other,

an enduring empire that lasted 2,000 years.

And in that sense, he did achieve a sort of immortality.

And he left this.

Guarded by the Terracotta Warriors

to the east

and flanked by elite tombs to the west,

a vast metropolis created for the First Emperor in death.

With its city walls, magnificent gateways,

and multiple palaces

to allow the First Emperor to commune with the living.

And beneath the surface,

everything from stables and chariots

to advisors and acrobats.

An entire royal court, ensuring he would rule for eternity.

At the very center,

the emperor's hidden tomb itself,

its lavish burial chamber guarded by booby traps

and packed with treasure,

his whole empire flowing with rivers of mercury

beneath a ceiling of constellations.

An entire city of extraordinary ambition and artistry.

A moment frozen in time for all eternity.

The greatest burial complex on Earth.

♪ ♪

♪ ♪