Original subtitles

NARRATOR: A bizarre discovery in Egypt,

along the banks of the Nile, has experts stumped.

- They find ten bodies in total, laid side by side.

But why were they buried here?

NARRATOR: A natural phenomenon

has gone unexplained for decades.

- These circles are a hotly debated mystery

amongst botanists, biologists, and ecologists alike.

- So what is creating them?

NARRATOR: And new discoveries unearthed in the Nile River delta

could solve the mystery of an ancient lost city.

- The more they dig, the more the sands reveal,

and this is no casual build.

NARRATOR: Astonishing discoveries unearthed

from the depths of the desert.

- (rattle snake hisses) - (wind swirls)

NARRATOR: Ancient lost cities...

forgotten treasures...

mysterious structures...

extraordinary curiosities,

once lost to the sands of time, are revealed.

As new technology uncovers

remarkable tales hidden beneath the deserts of the world,

the Secrets in the Sand will finally...

be exposed.

- (rocks crumbling)

- (wind whistling)

- (radar beeps)

NARRATOR: Around 700km south of Cairo,

across the Nile River from the town of Aswan,

is the ancient Egyptian site

of Qubbet al-Hawa.

- It's situated very close to the western edge of the Nile

and looks like a huge sand dune rising up from the riverbank.

- Perched on top of the hill is a small domed shrine

that gives the site its name: Qubbet al-Hawa,

which means "Dome of the Wind."

NARRATOR: The dome dates back to 2500 BCE.

While conducting fieldwork nearby,

a team of archaeologists discovered something incredible,

which dated back to the Byzantine Era.

- They find the remains of ancient crocodiles.

It's a bizarre sight.

- And it's not just a couple of crocodiles. They find ten in total,

laid side by side.

- (archaeologists chatter indistinctly)

HARIDY: Five are just heads,

but one is a nearly complete specimen,

measuring about 2m long.

The others range from 1.8 to 3.5m

and are in various states of preservation.

NARRATOR: After analysing the shape of the skulls

and the arrangement of the bony plates, called scutes,

the team determined that there were not only one,

but two different species of crocodile present.

- They found West African and Nile crocodiles,

both of which were native to the area.

They're very similar in appearance, but West African crocodiles tend

to be smaller and less aggressive than their Nile counterparts,

which are estimated to be responsible

for up to 200 deaths each year.

- (crocodile growls, munches)

NARRATOR: On average, Nile crocodiles are between

4 and 4.5m long,

weigh around 400kg,

and have a lifespan of 50-60 years in the wild.

While West African crocodiles

are typically between 1.5 and 2.5m long

and have a slightly shorter lifespan.

- Although West African crocodiles can still be found throughout

Central and West Africa, they have vanished from the Nile region.

This is probably because of climate change or human activity.

- (wind swirls)

NARRATOR: The crocodiles were remarkably well preserved

due to the extreme heat and arid conditions of the desert,

which aids in preventing rot and tissue damage over long periods.

Examination of the crocodile remains

revealed that some of them had bone fractures and lesions:

evidence of traumatic injury.

- One of the crocodiles has a healed fracture on its dorsal ribs

and two healed fractures on its ventral ribs.

Another has a healed fracture on its fibula

and lesions on its left metatarsal and right metacarpal.

But these injuries wouldn't have been severe enough to kill them.

They were likely the result of territorial fights.

- None of the bodies show signs that they suffered a violent death

at the hands of humans or other animals.

So, what happened to these crocodiles?

NARRATOR: Further investigation

found small fragments of linen with the bodies,

mostly eaten away by insects.

- Egyptians were known to wrap human bodies

in linen as part of the burial process.

Its presence suggests that someone buried

these crocodiles here for a reason.

NARRATOR: Ancient crocodile remains

have been found in other parts of Egypt,

most famously at Kom Ombo.

Approximately 50km north of Qubbet al-Hawa,

the town contains a temple dedicated to the god Sobek,

who manifested as a crocodile.

- Thousands of crocodiles have been excavated around Kom Ombo

and many were found to be wrapped in linen as part

of the mummification process.

So it's logical to conclude that the bodies found at Qubbet al-Hawa

aren't just regular crocodiles.

They're crocodile mummies.

NARRATOR: Animal mummification practices

were widespread throughout ancient Egypt.

Cats, baboons, cows,

hawks and even frogs

have all been discovered within tombs.

- They actually had breeding programmes that supplied a stream

of different animals, specifically to be killed and mummified.

It's been estimated that some

70 million animal mummies were produced over 1,200 years,

from around 800 BCE to 400 CE.

- And when animal supply was low, some shrewd entrepreneurs

produced and sold fake mummies.

The linen wrappings were stuffed with things like eggshells,

sticks and feathers.

NARRATOR: Along with the linen,

the team also discovered small pieces of rope around the remains.

- The rope means that the crocodiles

could have been tied up before death,

indicating that they could have been captive animals.

In terms of how they were mummified,

they could have been simply buried in the sand

in order to desiccate or mummify naturally.

LEONARD: Further testing is needed to determine their exact age,

but the bodies have no traces of resin,

which was used extensively in mummification,

starting around 300 BCE, during the Ptolemaic period.

HARIDY: When they investigate further,

the team notices that the croc mummies are surrounded

by simple rock structures,

that it's actually a rudimentary tomb

that's part of a much bigger complex.

But why were they buried here?

NARRATOR: Below the domed shrine and built into the hill

is one of the most densely packed cemeteries of ancient Egypt,

with hundreds of tombs dating as far back

as 2500 BCE.

- It's called the "Tombs of the Nobles"

and it's a truly remarkable place,

with four storeys of burial sites

gouged into the sandstone.

WEGNER: Many of the tombs are connected, most likely by family,

and although they aren't as well preserved

as other Egyptian burial sites,

there are hieroglyphic texts and painted scenes that tell stories

about the lives of their occupants.

NARRATOR: Most of the crypts follow the same basic floor plan:

an entrance hall, a room with pillars,

and a passage that leads to a burial chamber.

- The ones in the top tiers tend to be a bit more humble,

while the lower ones can be quite lavish.

The crocodiles were found lower down so maybe that means

they were mummified and buried as status symbols

for their owners in the afterlife.

- For ancient Egyptians, possessing exotic animals

showed wealth and influence.

At the ancient site of Hierakonpolis,

just over 100km to the north,

excavations have unearthed the remains

of elephants, leopards, baboons and even hippos

near the tombs of prominent citizens.

WEGNER: The Egyptians were known to keep dogs, cats and other animals

and if in a few rare cases, if a pet died before its owner,

it was mummified and placed in a tomb to wait for its master,

to keep him or her company in the afterlife.

But there is no evidence that the Egyptians kept crocodiles as pets,

They were feared as very dangerous creatures.

NARRATOR: One Egyptian ruler, Prince Thutmose,

went to great lengths to ensure his beloved cat

was afforded the kind of lavish lifestyle in the afterlife

as it was accustomed to whilst alive.

- The cat is buried in its own limestone sarcophagus,

ornately decorated with various scenes and hieroglyphics.

At the back, a cat is shown at a table piled high

with offerings to the gods, and a lotus flower,

the symbol of resurrection.

- But the crocodile mummies are just buried in the ground,

so it doesn't appear that they were treated like the pampered pets

of the upper echelon of Egyptian society.

What is going on here?

NARRATOR: A tomb of crocodile mummies

discovered beneath the domed shrine at Qubbet al-Hawa

left experts baffled and in search of answers.

Mummified animals were often dedicated

to the gods with whom they were associated

and could have acted as intermediaries

to carry a dedicator's prayer to that god.

- We think that such animals were raised in temples

and sold to worshippers for this purpose:

to serve as votive offerings.

So mummified crocodiles might have carried prayers to Sobek,

the crocodile god.

NARRATOR: The ancient Egyptians were known to worship Sobek,

a deity frequently depicted as a human

with the head of a crocodile,

who has a temple in his name at Kom Ombo.

- Sobek was a very important god.

The Egyptians were afraid of crocodiles, so they offered him

various things in an attempt to please him.

NARRATOR: People who lived along the river

relied on its flooding to fertilise their crops.

They believed their offerings were necessary to satisfy Sobek,

so that he would create an adequate flood.

- (crocodile growls) - To give an idea

of how seriously the Egyptians took these offerings,

there were crocodile priests whose sole purpose was

to mummify crocodiles and offer them to the gods.

They were treated and prepared virtually

the same way as human mummies.

- One mummy excavated at Kom Ombo

was found to have the leg of a cow in its stomach.

This suggests that it was fed by humans,

because in the wild, crocodiles mainly eat fish,

small mammals and small reptiles.

- This crocodile was also found to have over 25 mummified hatchlings

on its back. It's likely this was meant to symbolise

crocodile mothers in the wild, in order to represent fertility.

- Taking into consideration the meat found in its stomach,

as well as the hatchlings, this croc was probably a manifestation

of Sobek and may even have lived in the temple dedicated to him.

NARRATOR: Some offerings were considered

physical manifestations of Sobek.

Sacred crocodiles were raised in captivity

and respected as living representations

of the crocodile god.

- It's likely that the crocodile mummies

at Qubbet al-Hawa were votive offerings.

This is because there's no evidence to show that they were treated

with the reverence of the crocodiles at Kom Ombo,

so they probably weren't avatars for Sobek.

- Although the linen suggested these crocodiles were mummies,

there's no indication on their bodies that they underwent

an elaborate embalming process,

so they were likely naturally mummified before being buried.

NARRATOR: Despite their humble final resting place,

the crocodiles found at Qubbet al-Hawa

embody just how important these great beasts were

to the citizens of ancient Egypt.

It was a relationship based on equal parts fear and admiration

for one of the most awe-inspiring animals

on our planet.

- (radar beeps)

NARRATOR: The Namib Desert spans

more than 81,000 square kilometres

along Africa's western coast,

connecting the countries of Angola, Namibia

and South Africa.

- In the local Nama language, the word "Namib"

means "an area where there is nothing".

- (wind swirls)

- (hooves thumping)

- It's one of the most remote and inhospitable places

on the continent.

It has very low annual rainfall and extreme temperatures

that can reach as high as 45 degrees Celsius in the day

and fall well below freezing at night.

NARRATOR: 160km from the Atlantic Ocean,

a sliver of hyper-arid grassland that borders the desert

is mysteriously dotted with millions

of unusual circles.

- Best viewed from above, these strange,

oddly symmetrical and evenly spaced circles

are a hotly debated mystery amongst botanists,

biologists and ecologists alike.

- The Himba people of Namibia believe them to be

the footprints of Mukuru, the supreme creator.

NARRATOR: These rust-coloured spots

can range from 1.5m in diameter in the central Namib desert,

while in the northwestern region,

they can grow up to an enormous 25m across.

- Their uniformity in both shape and spacing

makes them look almost man-made,

like the work of a gardener gone wild.

However, the area is almost completely uninhabited,

except for a few small settlements and pastoral groups.

So, what are they?

- Because they look quite similar to "fairy rings'',

an arc of mushroom growth often found in forests and grasslands,

researchers have dubbed this phenomenon "fairy circles."

- (wind whistles)

NARRATOR: Fairy circles are barren spots of land

surrounded by tufts of healthy grass that grow across a landscape,

creating a periodic, evenly spaced,

dotted growth pattern.

Fairy circles develop, grow and die

as all plant life will,

depending on condition and environmental circumstances.

Through long-term tracking of their development,

and using mathematical calculation,

experts believe they have an estimated life span

of 41 years.

- Researchers have observed that some fairy circles

could be 75 years old.

It's even plausible that they've been around for centuries.

So, what is creating them?

HARIDY: One hypothesis stems from the notion

that decaying plants inhibit the future growth of plant life,

resulting in a particular pattern of barren land.

Is it possible a plant could be so toxic,

that it would leave scars on the landscape long after it's gone?

If so, the fairy circles, could they be those scars?

- The Euphorbia damarana, also known as Damara milk-bush,

is thought to be one of the most toxic plants in Namibia.

NARRATOR: Euphorbia damarana grows up to 3m tall

and between 3 and 5m wide.

Grey-green in colour, this succulent shrub

contains a milky latex that is not only toxic,

but capable of killing animals...

and humans.

NARRATOR: The Namibian "fairy circles"

have puzzled scientists for decades.

Could a deadly, toxic plant

be the evidence they were missing?

- Researchers found that the residual latex in the soil

where this plant and its cousin Euphorbia gummifera died,

resulted in faster water-infiltration rates.

This leaves the soil unable to hold water at the surface.

- Fairy circles appear similarly hydrophobic,

with the top 20cm of earth unable to hold water,

precisely where the grasses with shallow roots would need it.

- These researchers even believe

they can predict the size of future fairy circles

based on the relative size of these toxic plants.

NARRATOR: Researchers compared aerial imagery

taken over a period of 50 years,

to prove the euphorbia plants

were replaced with fairy circles when they died.

- However, a new research team returned

to the original area of study,

and using photographs, drone imagery,

and historic satellite images, they were able to prove

that new growth had in fact returned

to many of the locations where these plants had died.

So, if not toxic plants, what else could be the cause?

- Some researchers believe that these circular patterns

could be the handiwork of insects. And not just any insects.

The engineers of the insect world: termites.

NARRATOR: The continent of Africa

has the richest diversity of termites on the planet,

with over 1,000 species on record.

These subterranean insects live in colonies ranging in size

from a few hundred individuals,

to societies of several million,

and their mounds can measure up to 9m high

and 7m wide.

- Termites are integral to the fertility

of the world's arid grasslands

and their colonies can even directly influence landscapes.

- Savannas with a significant number of termite mounds

are more likely to survive with much less rainfall

than those without termites.

NARRATOR: Termites clear out vegetation,

allowing rainfall to filter deeper into the ground,

to hydrate a colony for the entire year.

As a result, these insect-rich grasslands

offer much-needed lifelines to local plant and animal life,

by creating areas of comparative biological abundance

in their immediate vicinity.

CANTOR: These industrious insects have been known

to create patterns in a landscape.

Perhaps termites are eating the roots of the grasses,

and systematically killing them.

Could this be what is creating these circular designs?

- However, termite mounds tend to result

in the mirror image of fairy circles.

Where fairy circles are defined by the absence of growth,

surrounded by vegetation,

a termite mound tends to feature an island of growth

surrounded by dry land.

- While there are a few species of termites living

in the area of the circles, there does not appear to be

a sufficient food source for the volume of termites

that would be necessary to create patterns on such a large scale.

NARRATOR: In 2014, near-identical fairy circles

were discovered over 10,000km away,

in the outback of Australia.

CANTOR: Research teams converged on the area

and dug holes inside the fairy circles

to assess the presence and influence

of Australian termites on these patterns.

RESEARCHER: And there's no sign of...

termite herbivory.

- Ultimately their findings did not show a relationship

between the termites and the patterns.

NARDI: By comparing aerial footage of vegetation gaps

created by termites, researchers found that the termite patterns

were much less organised and smaller than the circles.

So clearly, insect activity is not producing the fairy circles.

So, what is causing this puzzling phenomenon?

- (wind swirls)

NARRATOR: Annual rainfall across the Namib Desert

ranges from less than 2mm to 200mm,

but within this specific strip of dotted grassland

the maximum rainfall is 120mm.

- With the incredible heat of the Namib Desert,

water loss happens very quickly due to absorption,

evaporation, and transpiration.

- New research suggests that when under stress due to drought,

the grasslands have to reorganise themselves.

- If this strip of the Namib received

a few millimetres more of rainfall,

the grasslands would show uniform growth,

like the hardier grasslands to the west.

So, why are the grasses dying off in this pattern?

- Immediately after the rains,

grass will grow in all areas, filling in the circles.

But researchers noticed that within the following 20 days,

young grasses at the centre will die.

NARRATOR: The older, more mature grass

appears to pull water away from the centre, towards the edges,

creating a vacuum effect, that can exist over great distances.

HARIDY: The grasses themselves are engineering

the environment to their benefit.

They are maximising the rainfall through the creation

of these fairy circles and the result is

this beautiful, dotted landscape.

If proven to be true, it's a stunning story

of survival under the harshest of circumstances.

NARRATOR: In the end, the theories behind the fairy circles

are still up for debate and greater research is required

in the grasslands of the Namib desert

to determine their ultimate origin.

Until then,

they remain an awe-inspiring landscape to behold.

- (radar beeps)

- (insects chirp)

NARRATOR: 140km north-east of Cairo,

in the province of Sharqia,

is an area of dry, rural land

that lies along the eastern Nile River delta

and the town of Tell el-Dab'a.

- People have settled this area for millennia.

Here, on the edge of the desert,

is one of the cradles of human civilisation.

NARRATOR: Archaeologists interested in the mysteries of ancient Egypt,

have visited the Nile delta for years.

Through a combination of persistence, determination

and advanced technology, a team of researchers

uncovered something lost to the world for millennia.

NARDI: Buried beneath layers of earth and sand

are the remnants of a large structure

constructed of sturdy sandstone bricks.

WAKEFIELD: It's a massive 7-8m wide

by 500m long white stone wall

buried along the town.

The more they dig, the more the sands reveal.

And this is no casual build.

NARRATOR: The ancient complex covers an area

of over 2 square kilometres

and appears to have been built up over a long period of time.

- Excavation is difficult

given the number of local residents and established farming communities

currently living and working on the land.

NARRATOR: A combination of traditional archaeology

and modern scientific techniques,

including core sampling and geomagnetic surveying,

was used to ascertain the full picture of the site.

ELLIS: It's a huge footprint.

There are courtyards, residences, streets,

temples and so much more.

It appears to be an entire settlement, or ancient city.

- In ancient times, the site would have been connected

to the Mediterranean and the Nile Valley,

offering clear strategic benefits

with access to the land, river, and sea.

NARRATOR: The Pelusiac branch of the Nile,

like many of the other ancient Nile branches,

disappeared a long time ago,

due to a variety of human and natural factors.

- The Nile River was critical to the development of ancient Egypt,

and most of its villages, towns and cities were built along its banks.

It was not only the main mode of transportation,

but also the primary source of clean drinking water

throughout the arid countryside.

- One would assume that this city would be automatically

attributed to the ancient Egyptians, but something here is off.

- Even though the structures are made of traditional

Egyptian building materials, this site has a more random,

disordered plan than one would expect of Egyptian urban design.

That's kind of strange. Who else could have built it?

NARRATOR: Continued excavation and imaging of the enormous site

not only revealed more of the layout,

but also exposed the timeline of construction

through the differing sedimentary layers.

Experts believe that this site

was continuously occupied for thousands of years.

- This site is a historical puzzle.

There are foundations on top of foundations,

newer, larger stone structures

built directly over top older ones.

It's mind-blowing!

One area of the site features a structure,

likely a palace, built directly on top

of a series of much older foundations.

- This ancient village or settlement includes

more than 342 four-roomed,

mud-brick residences.

They were very small, even for that time.

NARRATOR: Archaeologists believe this is the first and oldest

mud-brick settlement in the region,

and date the structure to sometime between

1963 and 1934 BCE.

- The ceramic fragments discovered in this layer of earth include

red-polished pottery and simple clay vessels,

likely from Upper Egypt. These findings indicate that

this early structure was from a purely Egyptian settlement.

- Eventually, these homes were abandoned,

and newer structures were built on top.

And that's where things begin to get weird.

They include a foundation of a surprising,

clearly foreign building.

WEGNER: The plan of this structure is reminiscent of a type of home

that would be found in northern Syria, not here in Egypt.

The existence of this home signals the presence of foreigners,

non-Egyptians who settled in the area.

- Given the authentic style of the home, the people who built it

and lived here likely came from an area known as the Levant,

that's centred around what is modern-day Palestine,

Syria and Jordan.

- The Levant was a region encompassing the countries

surrounding the eastern Mediterranean.

It extended from modern-day Turkey to the north,

including the coastlines of Greece, down to Egypt in the south.

The region was highly populated and well-travelled for the time,

home to ancient trade centres and routes.

So, perhaps this was a Levantine outpost?

NARRATOR: At another site within the compound,

archaeological teams uncovered a much larger,

more palatial residence, in keeping with Egyptian designs.

It is named "Palace Necropolis"

for the cemetery within its walled enclosure.

Researchers examining the cemetery concluded

the site spanned two entirely different periods of time.

- The new tombs have been built next to older tombs.

NARRATOR: The later tombs have been built in a manner

that preserves the integrity of the old tombs.

- The earlier graves are likely from the 1900s BCE

and they are simple and shallow, containing

few offerings for the afterlife.

Some also contain multiple people, as well as animals.

- Dated approximately 350 years after the first

purely Egyptian settlement, these newer tomb designs

and goods indicate both the economic growth of the community,

as well as increased contact with foreigners.

NARRATOR: Researchers analysed the teeth of 75 of the remains

taken from the various cemetery layers.

24 people were found to be

foreign-born residents of the community,

indicating a distinct diversity of peoples

living in direct proximity.

- The remains tell the story of an increasingly diverse population

seemingly living and dying in harmony.

So, what was happening here?

- Though most of Egypt's history is well documented,

there is a period of about 100 years that we know little about,

except for stories written 1500 years later by an Egyptian priest

named Manetho in his book 'Aegyptiaca.'

- This one book told stories of foreign invaders

taking over Egyptian cities to rule the land.

These evocative accounts took hold in the minds

of Egyptians and Egyptologists alike.

- This history refers to a capital city called Avaris,

and generations of Egyptologists began looking for it

as far back as 1880.

So, could the modern site of Tell el-Dab'a

actually be the lost city of Avaris?

NARRATOR: Exploring further, archaeologists uncovered

what appeared to be another large palace complex.

Within the grounds, they found the remains

of a broken limestone door jamb

with carved impressions.

- The hieroglyphic impressions on the door jamb connects

to the Hyksos, of the Fifteenth Dynasty of Egypt.

The word Hyksos is Greek, meaning "rulers of foreign lands."

- This palace is clearly not Egyptian in style.

It appears to feature courtyards,

temples and multiple residences,

but it lacks that classic Egyptian design balance.

NARRATOR: Ancient Egyptian architecture often featured

ordered, structural symmetry

reflecting the concept of balance and harmony

that they also sought in life.

The Luxor Temple, The Temple of Ramesses III,

and the Temple of Isis

are all beautiful examples of this design.

- This site shows more similarities to palaces

built in Syria than it does to local designs.

- Within this courtyard, there are offering pits

with thousands of pieces of broken pottery,

many from the Levant and other foreign regions,

as well as animal bones.

This assemblage of objects implies that it was the site

of great feasts and celebrations.

- Not only are there pits with what appear to be

offerings from a ritual feast,

but other nearby pits contain something that is entirely bizarre:

severed human hands!

NARRATOR: Near the modern city of Tell el-Dab'a

along the ancient Nile River, experts may have finally

identified the lost city of Avaris

and the mysteries of its inner workings.

The discovery of severed human hands

could be evidence of an ancient Egyptian practice

known as "gold of valour."

This was a practice where soldiers would exchange

the severed right hand of their enemy,

proof of their victory in battle, for gold from their leader.

- Discovered near the palace throne room, likely used by King Khyan,

there are a total of 16 right hands.

- It's a truly gruesome find.

The hands have been dated to around 3,500 years ago,

towards the end of the Hyksos reign.

WEGNER: To cut off a dead enemy's hand

was an efficient way of counting casualties,

and the hands were piled up and counted by scribes

as the basis for awarding the "gold of valour."

These 16 hands are the first pieces of physical evidence

for a practice that, until now, has only been documented

in Egyptian art and writing.

NARRATOR: Tell el-Dab'a is now believed

to have once been the city of Avaris,

the Hyksos capital that flourished between 1650

and 1550 BCE.

It was eventually reclaimed by the Egyptians

when the pharaohs of the Eighteenth Dynasty

laid siege and took the city back.

- The most interesting part of this discovery is not

that the city was foreign-ruled, but that there are no signs

of forced invasion or violent takeover by the Hyksos,

as told in the stories of Manetho.

Instead there are hundreds of years of evidence

of cohabitation and collaboration between immigrants and locals.

NARRATOR: This site may never be entirely excavated,

nor will its finds ever be complete,

due to looting and continued modern development in the area.

But the location is proof

that the Nile River delta has always been a draw

for many people of the world.

- (wind swirls)

- (radar beeps)

NARRATOR: The Pisco Valley on the Nazca Plateau

is situated near the southern coast of Peru,

around 250km south of Lima,

the country's capital city.

- There are three basic geographic regions in Peru:

the Selva, which is Amazon rainforest,

the Sierra, which is the highlands of the Andes mountains,

and the Costa, which is the coastal region.

- The Nazca Plateau is in the Costa,

nestled between the Pacific Ocean and the Andes.

It's mostly arid, rocky hills.

NARRATOR: A pilot conducting an aerial survey of the valley

spotted something strange on the ground below:

a long strip of evenly spaced depressions,

weaving its way through the jagged landscape.

- He can't figure out what it is.

It looks like a tyre track from a huge bicycle

that someone rode through the hills.

It's enormous, really a sight to behold.

NARRATOR: The band begins at the mouth of the Pisco Valley

and ranges in width from approximately

14 to 21m,

and snakes its way uphill

for almost a kilometre and a half.

ELLIS: It sticks out like a sore thumb.

Clearly, this has to be man-made.

Formations like this simply don't occur naturally.

But what is it?

NARRATOR: Ground-level investigation at the site

revealed that the band was made up of circular holes.

Thousands of them.

- It's estimated that there are between 5,000-6,000 holes

measuring around 1m in diameter

and varying in depth between 50 to 100cm.

- There are three different types of holes:

some are raised off the ground with rocks,

others appear to be dug into the side of the hills

and some are standard holes with soil lining the edges.

NARRATOR: Locals call it "Monte Sierpe,"

which translates to "Serpent Mountain,"

likely due to its snakeskin-like appearance.

It's also known simply known as the "Band of Holes."

Searching for answers,

researchers turned their attention a couple of hundred kilometres south

to Peru's famous Nazca lines.

- The Nazca lines are one of the world's largest geoglyphs,

spanning some 500 square kilometres.

There are more than 800 straight lines,

300 geometric shapes,

and 70 plant and animal designs called biomorphs.

- Given their relative proximity to each other and because they're both

large-scale manipulations of the earth,

some observers propose that maybe the Band of Holes

is a form of ancient geoglyphic art.

- I suppose it's possible,

but the Nazca lines clearly form images,

while the Band of Holes doesn't appear to have any real order to it.

NARRATOR: Around five kilometres from the site,

a huge 15th-century Inca complex

called Tambo Colorado can be found.

- Tambo Colorado was very important to the Inca empire.

It was a regional centre of economic,

cultural and administrative activity.

- It's a pretty impressive place with several large structures

surrounding a central plaza

And because of the hot, dry environment,

it's remarkably well preserved.

- The complex is strategically located on what was a main road

that connected the coast to the inland region.

Here, the Inca could control the flow of goods

and monitor access to water sources,

so it makes sense that they may have wanted

to safeguard it against attack.

NARRATOR: Experts have proposed

that the Band of Holes was built by the Incas

as a defensive structure to protect this vital hub.

- They could've been foxholes — pits dug into the ground for cover

against attacks or used as firing positions.

Or maybe they were obstacles designed to slow down the enemy.

NARRATOR: Doubters are quick to point out

that if the Band of Holes was a defensive structure,

then military artifacts would have been discovered there,

yet none have been found.

- Strangely, no artifacts whatsoever

have been discovered in or around the holes.

But researchers working nearby recently found

small amounts of pottery dating to the Late Horizon period,

which was between 1450 and 1533 CE,

a time when the Inca Empire grew to dominate most of the Andean region.

- Given the dating of the pottery

and the proximity to Tambo Colorado,

it's safe to assume that the Band of Holes was built by the Inca.

NARRATOR: The Inca were known to use foot ploughs and stone picks,

and it's been estimated that a healthy young man

could probably construct one of these holes fairly easily,

within just a few hours.

- For projects like this, they worked in teams of 10, 50,

100 or even 500 men.

And if you do the math, a group of 100 men

could've completed the Band of Holes in around a month.

- The Inca were famous, very skilled engineers,

who constructed majestic sites like Machu Picchu.

They also built and sustained

the longest road system in pre-Columbian South America

through one of the most challenging terrains on the planet.

So it's entirely reasonable that they could have constructed

the Band of Holes with relative ease.

- They had the skills, they had the resources,

they had the manpower to build it, but that still

doesn't answer the question of what exactly it is?

NARRATOR: Discoveries made at Inkawasi,

an Inca centre similar to Tambo Colorado,

120km away,

may finally solve the riddle of the Band of Holes.

- Archaeologists unearthed a checkerboard pattern

built into the floor of a huge open room.

There are 3,510 squares,

all measuring 23cm by 23cm,

and they were found to contain traces of food.

- They also discovered quipus, which are knotted string

counting devices used by Inca state accountants.

- It's believed that the squares on the floor were used by citizens

to measure out tributes to the Inca state;

a form of taxation.

- People would fill up their sections with produce;

beans, grains, peppers, squash, whatever they had to offer,

and the accountants would record whatever they had given.

NARRATOR: Researchers can't help but notice

that despite the difference in scale,

what was found at Inkawasi does bear some resemblance

to the layout of the Band of Holes.

- It could be an improvised regional adaptation

of the checkerboard system, born out of necessity.

- Tax tributes were likely taken to Tambo Colorado,

so the Band of Holes would have been an ideal place

for people to stop and measure their produce.

- There were no artifacts in the holes,

meaning that they could have been used to store perishable goods

or items that were put there temporarily,

leaving no trace behind.

NARRATOR: Drone images of the site also reveal something

that had previously gone undetected:

distinct patterns in the layout of the holes.

- When analysing the pictures, they notice that the holes

seem to be divided into segments,

each one with a recognisable pattern

in terms of both orientation and the number of holes in each row.

CANTOR: Some segments have a diagonal arrangement

with a 1-3-5-7-9-11-11 pattern

in the number of holes per row.

Other segments contain perpendicular east-west rows

in a 6-6-7-7-8-8 pattern.

- Each segment was probably devoted to a tax-paying group,

maybe an extended family

or a regional association of individuals.

NARRATOR: In order to confirm their hypotheses,

the team hope to conduct future thorough soil analysis.

- If the holes were used to measure produce,

there will likely be remnants of plant tissue or pollen left behind

which could be tested to determine the dates when food was present.

- It could be a major step towards broadening our knowledge

of the Inca taxation system

as well as Inca civilisation as a whole.

NARRATOR: Should the Band of Holes be proven a taxation site,

it will further illustrate that even in the ancient world,

the only certain things in life

were death and taxes.

Subtitles by Sky Access Services