All language subtitles for Discovered.by.Disaster.S01E07.1080p.WEB.h264-BAWD_track3_[eng]

NARRATOR: Scientists uncover
underwater remains

of what could be
a long lost Egyptian city.

- Historians could never determine
exactly where in Egypt

it was supposed to have been.

- We've never seen any proof
it actually existed.

So could the city have
finally been discovered.

NARRATOR: After an extinction level
event that killed the dinosaurs,

new discoveries reveal
a thriving ecosystem.

- This is strange
because you would assume

that the closer you are
to the impact crater,

the longer it would take
for life to rebound.

NARRATOR: Workers uncover strange
markings left in the wake of

a volcanic eruption.

- The scoria was lying above
a layer of volcanic ash,

which is what protected
these strange imprints

over the course of
thousands of years.

NARRATOR: All over the world

incredible discoveries are being
revealed by devastating events.

Floods, earthquakes, droughts,

hurricanes, volcanic eruptions,

trails of destruction expose
long lost mysteries.

This is Discovered by Disaster.

In 140 BCE,

a fabled, opulent and powerful
ancient port in the Nile Delta,

the revered gatekeeper
of Egypt's riches,

is stricken by a sudden
devastating calamity

that sends its greatest monuments
tumbling into the shallow waters.

- This once legendary city
never fully regained its glory.

And as the years
and centuries passed,

it sunk ever deeper into the water
and mud until every trace vanished.

NARRATOR: In the late 1990s,

a team of archaeologists were hoping
to locate the wrecks

of late 18th century
French warships,

which they had reason to believe
sank somewhere in the waters

of Egypt's Bay of Abu Khdeir.

Using a nuclear magnetic resonance
magnetometer to scan the sea floor,

the team gets a hit,

but whatever's there
is much bigger than a shipwreck.

- The water is only about 20ft deep.

And on the bottom, veiled in silt,

is a huge line of massive
rectangular limestone blocks,

a wall and it's ten feet thick.

Just the part that's visible
at this point is at least 65ft long.

It's clear there's something
significant here, but what?

NARRATOR: A team of divers
is sent to investigate

and they find huge pieces of stone
scattered about like gigantic dice.

The massive fragments are
painstakingly raised and studied.

The results leave
the archaeologists stunned.

- They're pieces
of huge stone statues.

One of them is
a male figure about 18ft tall.

He's in mid stride

and is carrying some kind of tray
with four loaves of bread on it.

- The forward striding pose

signifies he's about
to offer something

while the tray is what's known as
an offering table.

So the interpretation is that
the statue is offering abundance,

the abundance symbolised
by the loaves of bread.

This is likely the Egyptian God
Hapi, the Father of the gods,

the source of everything.

The other gods, the world, food,
all of humanity.

- It makes perfect sense that
this towering statue of Hapi

would have been positioned
at the Nile's mouth,

welcoming ships coming
to the kingdom of Egypt

from the outside world.

NARRATOR: The jumble of
other colossal stone fragments

yields even more potent symbolism.

- The rest of the pieces belong
to a pair of statues,

a male and a female
carved out of pink granite

and standing about 16ft tall.

The pair dressed
in a distinctively Egyptian way.

The woman is wearing
the same headdress as a god Isis.

So this has got to be
a royal couple. But who exactly?

NARRATOR: As the underwater
excavations continue,

more sections of wall are found.

And for the archaeologists,
something begins to take shape.

- This was some sort of building,
but of truly impressive proportions.

Larger than 35,000 square yards,

built out of huge limestone blocks.

Radiocarbon testing reveals that
it was probably erected

between 450 and 380 B.C.

NARRATOR: For archaeologists
well versed in Egyptian

and Greek writings,
the presence of the wall

and these colossal statues
sparks a realisation.

- In the fifth century BCE,

the Greek historian Herodotus wrote
about an amazing city

built on islands in a marsh.

Though he said the city was
in Egypt,

he simply referred to it
as Heraklion,

which means
the place of the temple of Herakles,

and Herakles was a Greek god.

But historians could never determine
exactly where in Egypt

this city with a Greek name
was supposed to have been.

- The ancient Egyptians had records
of an island city as well,

somewhere at the gateway
to the Mediterranean,

the mouth of the Nile.

But they called it Thonis.

But we've never seen
any proof it actually existed.

So could be cities have
finally been discovered.

NARRATOR:
Near the ruins of the wall,

archaeologists discover
a large cabinet-like structure

nearly six feet tall,

masterfully carved from
a single block of pink granite.

- The roof is pyramidal in shape

and at the corners of the top and
bottom edges of the front opening,

there are holes,
almost like pivot holes for hinges.

That tells us this cabinet once had
double doors

that, along with where it was found,
suggest that it was a naos.

- A naos is a kind of shrine
that would have held a statue

or other religious artifacts.

So is this huge wall
part of a temple?

NARRATOR: Further examination
of the inside surfaces of the naos

reveals faint remains of
chiselled writing and hieroglyphics.

- The hieroglyphics contain the name
of the God in whose temple

this naos would have resided.

It's the temple of Amun-Gereb.

- According to the inscription,

the God Amun-Gereb would bequeath
to each new Pharaoh

everything in their earthly
and heavenly kingdom,

basically making them
a king entitled to own everything.

NARRATOR: In 1866,

archaeologists excavating
the ancient town of Tanis,

just 100 miles east,

discovered two copies
of a stone slab

bearing Egyptian
hieroglyphic writing.

- It's known as
the Decree of Canopus,

and it talks about the god
Amun-Gereb and his temple.

And it names the town in which
his temple stood, Heracleion.

- So now we know conclusively

the lost city that Herodotus
wrote about did exist.

And this is it right here.

This is Heraklion,

and this massive temple
of Amun-Gereb would have been

at the heart of it.

NARRATOR: As the underwater
excavation progresses,

more walls are found, but not all of
them seem to belong to the temple.

Some form a network of large
trenches surrounding the building.

- Samples of the silt between
the walls reveal

that these are canals
running around the temple,

which would have been accessed
from other buildings

by way of ferries and bridges.

Heraklion was like
an ancient Egyptian Venice.

NARRATOR: In the area
where the canals used to be,

a great number of wrecked ships
and boats are discovered,

as well as many artifacts,

including coins attesting
to the city's great wealth.

- Interestingly,

a disproportionate number of
the coins found are identified

as being minted between
the 6th and the 4th centuries BCE.

This must have been
when Heraklion was at the peak

of its prosperity and power.

NARRATOR:
The discoveries keep coming,

including one found within the
grounds of the temple of Amun-Gereb

that astounds the archaeologists.

- It's an inscribed stone tablet
known as a stele,

6.5ft tall
and in excellent condition.

The hieroglyphics carved into
its face are completely legible.

It turns out the stele bears a royal
decree by the Pharaoh Nectanebo I.

This decree even bore a date
which in our modern calendar

equates to 380 BCE.

- The decree states that
this stele should be

"erected at the entrance
to the Sea of the Greeks."

That would be the Mediterranean,
in a town by the name of Sais.

This is amazing.

We already know that another
Egyptian name for Sais is Thonis.

- The stele confirms once and
for all that Thonis and Heraklion

were the same legendary port city.

So what happened
that made it disappear?

NARRATOR: Buried deep under
16ft of hard packed clay

alongside the ruins of the temple
of Amun-Gareb

and under heavy limestone blocks,

the archaeologists discover
the wreck

of an 80 foot long wooden ship.

- The ship's hull dimensions
made it fairly sleek,

so it might have been a warship
or possibly a vessel

used by customs officials
to police the Nile Delta

and keep money flowing
into the royal coffers.

- At the time of
the ancient cataclysm,

this vessel was likely
moored alongside the temple.

When disaster struck
and the temple collapsed,

some of its huge limestone rocks
smashed down onto the ship

and immediately pressed
its remains deep into the mud.

But what was this cataclysm?

NARRATOR: Magnetic mapping
of the area reveals the presence

of a number of faults or rifts
that cross the temple grounds.

- These rifts likely resulted
from a soil liquefaction event,

which is when water saturated soil,

like you might find
in a river delta,

is subjected to vibrations
like an earthquake.

Vibration causes the soil
to momentarily behave

like a vicious substance
incapable of supporting any weight.

- The ground turns suddenly
and briefly into a muddy soup.

The temple of Amun-Gereb collapsed.

Some of its enormous limestone
blocks pinned that moored ship

to the bottom, along with
artifacts from the temple,

preserving a snapshot
of that moment in time.

- From approximately
the year 140 BCE on,

it's clear from
the archaeological record

that the flow of coins into the city
of Thonis-Heraklion all but stopped.

So that strongly supports
an estimated date of 140 BCE

for the cataclysm.

- But the city wasn't completely
destroyed at that time.

There's evidence that people lived
there for the next eight centuries.

However, over the years,
the sea level continued to rise

and the buildings
of Thonis-Heraklion sank

under their own weight,
deeper and deeper into the mud.

By 800 CE following a series
of earthquakes and tidal waves,

all trace of the once legendary city
was gone.

NARRATOR: Few people today
have heard of Thonis-Heraklion,

but chances are that will change.

As we learn more about
this great, doomed city,

we'll be forced to rethink
what we know of the past

and perhaps to reevaluate
our thoughts

regarding the permanence
of humanity's great port cities.

NARRATOR: 66 million years ago,

the mother of all disasters
tore the entire earth apart.

Not a single corner of the planet
was left untouched

as the energy from an asteroid
impact set the world on fire.

- This asteroid measured
six miles in width.

Think about that.

That's like something bigger
than Mount Everest is tall,

smashing into the earth
at 150,000mph.

It hit the earth in and around
what is today

Mexico's Yucatan Peninsula.

And when it did hit,

the result was apocalyptic
in the truest sense of the word.

- It generated an enormous tsunami,

the size of which is difficult
for us to quantify.

Then an unbelievable amount
of energy created by the impact

set off a chain reaction of hell

triggering earthquakes
as far south as Argentina.

-To put how big of an explosion
this was into perspective,

take the biggest nuclear explosion
ever created by humans -

the Tsar Bomba set off by
the Soviets in the 1960s.

It measured 50 megatons,

while the impact created
by this asteroid

would have been equivalent
to a 20 million megaton explosion.

- Basically, what this meant
was the equivalent

of a one megaton hydrogen bomb
going off every six kilometres

all across the planet.

It was like the gods poured gasoline
over the earth

and put a match to it.

Everything.
Absolutely everything was on fire.

NARRATOR: With all the debris that
was launched into the atmosphere,

the fallout from the blast
created an impact winter

which blotted out the sun
for at least a year.

This meant that everything
that relied on sunlight for life

also died.

- This is what we call
an extinction level event.

Actually, it's the extinction level
event of the past 66 million years.

This is the asteroid
that killed off the dinosaurs.

As a result of
the asteroid's impact,

75% of all of
the earth species died.

- We know about
the extinction of the dinosaurs,

but what about the 25%
of species that survived?

How did life on earth
not just continue,

but continue evolving when
the planet was one massive ashtray?

NARRATOR: The 20 mile deep
and 100 mile wide crater

created by the asteroid's impact
is known as the Chicxulub Crater.

In 2016,

a team of scientists were taking
sediment samples from the crater

in the hope of learning more
about the planet

in the years following
the impact event.

- So in these sediment samples
taken from deep down in the crater,

roughly 2000ft below the sea floor,

there are tiny little burrows,

as well as the fossils
of a very particular organism.

- These are
the tiny little sea creatures

like plankton and foraminifera,

a shelled micro-organism
populating the world's oceans.

The thing is,
there are a lot of them,

they're diverse and seem to have
been flourishing.

The sediment cores represent
the time from only

30 to 200,000 years after impact.

So how on earth did life
in the ocean rebound so quickly?

-This is strange because
you would assume

that the closer you are
to the impact crater,

the longer it would take
for life to rebound.

When an asteroid hits
the earth like this,

a lot of things are killed
and decompose.

And when they do,
they consume oxygen.

So if the oxygen isn't replenished,
somehow life suffers.

NARRATOR: The 35 million year old
Chesapeake Bay crater

was formed by a much smaller
asteroid than the Chicxulub

at only 2 to 3 miles wide.

Nevertheless, it still would have
had a serious impact

on the surrounding environment
when it hit.

Following this impact event,

the area of the crater
became anoxic,

meaning the ocean was
without sufficient oxygen

to sustain life as diverse
as that of Chicxulub.

- The Chicxulub crater is massive,

but its northeastern section is
and was open to the Gulf of Mexico.

This means that there could be
circulation of seawater

in the crater, which in turn
would allow for life to rebound.

On the other hand, the shape
of the Chesapeake Bay crater

probably made this very difficult.

Meaning that the ocean water
remained stagnant.

- So despite the entire world
being devastated,

the ocean environment
in the impact crater

actually rebounded
extremely quickly.

Which is really incredible.
But what about life on land?

How long did it take for ecosystems
and animal life to recover?

- To find out,
we need to look at the fossil record

from the years before
and after the event.

We know that the biggest mammals
that existed during the time

of the dinosaurs were only
as big as your average rat.

But we have almost no evidence
of what animals survived or evolved

in the thousands of years following
the Chicxulub impact event.

NARRATOR: A few decades ago,

a group of palaeontologists were out
hunting for fossils

in a known hotspot
for dinosaur bones,

Colorado's Corral Bluffs.

When one of them stumbled upon
a fossil embedded in a curious rock.

- It was the palate of a mammal
that was set in a concretion,

which is a rock that over time
forms around organic material,

which in this case is bone.

NARRATOR: The find alerted
scientists to the idea that maybe,

just maybe,

more such fossils could be found
encased in concretions.

So they began scouring
the Corral Bluffs,

quickly discovering several fossils
encased in concretions

from around the time
after the apocalypse.

- One fossilized skull has
these sharp, jagged teeth

in the front of its mouth,

whereas in the back,
the teeth are broader and blunter.

This indicates that it can eat
both meat and plants.

If the ecosystem of the entire world
has been nearly destroyed,

it would be beneficial if you could
eat everything,

which it appears this animal
named the Loxolophus could do.

- It also has a hole
underneath its eye.

This was a passage through
which nerves could travel,

so it probably had
very sensitive whiskers.

And the shape of the skull also
indicates that a big portion of it

was dedicated to smell.

What we're looking at here is
maybe an omnivorous,

highly adaptable,
raccoon-like creature

that could scavenge
what little food was available.

- So quite early on, only around
100,000 years after the event,

we're seeing bigger animals
than rats living in

the post-apocalyptic world.

Mammals that were more specialised,
like plant eaters,

wouldn't have been able to survive
the catastrophe

and would have been among
the 75% that went extinct.

NARRATOR: As the scientists continue
searching the coral bluffs

for more fossils,

they discover a much larger skull
than that of the Loxolophus

dated to around 300,000 years
after the asteroid impact.

- This mammal has huge teeth
that would be used more

for grinding than for tearing.

Which means
that it was a vegetarian.

What this tells us is that
in the intervening 200,000 years

between the Loxolophus
and this plant eater,

mammals had become specialised.

- On an evolutionary timeline,
this is very fast.

But in order for this
to have happened,

the environment would have
to support such a diet.

There likely would have been
a wide variety of plants available,

otherwise it simply wouldn't
have enough food

to have been so highly specialised.

- So after 300,000 years,

the forest environment appears
to have recovered fully,

and along with it, the mammal
population began to explode.

NARRATOR: Two more skull fossils

dating to 300,000 years after
the impact event are discovered

in the Corral Bluffs.

One has large incisors, whereas
another has very flat back teeth.

- The shape of their teeth shows us
that they each had different

plant based diets and judging by
the size of their skulls,

the mammal with large incisors
would have weighed around 80 pounds,

whereas the one with the broad teeth
would have been even bigger

and could measure up to 170 pounds.

- This is incredible because
their size, relative to the size

of the mammals living only
a few hundred thousand years earlier

prior to the extinction event
were way smaller.

We have seen this before, mammals
growing significantly in size,

but we've seen it over
a 30 million year time frame,

not one of less than
a million years.

It's pretty rapid. So how did
they get so big, so fast?

- Again, we have to look at their
diet and the food available to them.

The existence of these mammals
tells us

that the ecosystem had rebounded
quite well

as only a healthy,
diverse environment

would be able to support
such large animals.

Without protein rich foods,
they could never attain such a size.

NARRATOR: Still working
in Colorado's Corral Bluffs,

scientists unearth
another concretion,

this time inside the rock
is a rounded, oblong fossil.

- This is the fossil of a bean pod,

and it's dated to
about 700,000 years

following the asteroid's impact.

- Legumes are incredibly nutritious,
even today.

They are an essential food source
for billions of people,

and because they provide such
a good amount of calories,

eating them would also
be highly advantageous for mammals

living millions of years ago.

- Eating these plants led
to the evolution of mammals

the size of a modern day wolf,
weighing roughly 100 pounds.

These creatures were
a hundred times larger

than those that survived
the mass extinction

a few hundred thousand years
earlier.

The speed at which all this happened
is remarkable

and entirely unexpected.

It shows us
how life always finds a way,

even in the hardest
of circumstances.

NARRATOR: The collapse triggered
by the Chicxulub impact

was one of five mass extinctions
that occurred

in the last 450 million years.

And the frightening reality is
that this kind of natural,

apocalyptic event could happen
at any time.

And who knows if the planet
will rebound next time.

NARRATOR: In 1431, after years
of unprecedented drought,

Angkor Cambodia, capital of
the mighty Khmer civilization

was experiencing high levels
of instability.

- This enormous city with
its beautifully ornate temples

and highly sophisticated
urban infrastructure,

was attacked by
its number one enemy,

the people of the Ayutthaya kingdom,

who arrived from their homelands
to the west.

- The Ayutthaya burned Angkor.

Anarchy reigned
and the population fled en masse.

Their invasion also disrupted
critical supply and trade

into the city, which contributed
to its total abandonment.

-The collapse of Angkor,

one of the greatest cities the world
has ever seen

has long been a mystery.

The site has been studied for
over 100 years,

yet there has been little concrete
historical evidence

to truly explain why it collapsed.

So there must be more to the story.

NARRATOR: Almost 600 years after
the fall of Angkor,

a team of researchers

from the Tree Ring lab
at Columbia University are trying

to create a holistic picture
of the time period.

Working in Vietnam's Bidoup Nui Ba
National Park,

they began drilling holes
in old trees

in order to extract a core sample.

- Trees are incredible bookkeepers.

Their growth rings contain
a detailed record

of the environmental conditions
they've experienced

over their lifetime.

Each ring corresponds
to one year of growth.

Generally speaking, if one year
the rings are spaced further apart,

it indicates that conditions
were optimal for growth

and the tree grew more.

If they're spaced closer together,
it means conditions weren't as good.

And so the tree grew less.

- This remote section
of the park is pristine,

and the trees that were sampled
are over 1000 years old.

Some of them dating back
to when Angkor was at its peak.

And it's relatively close.
So historically,

it would have experienced the same
environmental conditions.

- A sample taken from a cypress tree
revealed an environmental record

starting in 1030 CE
and ending in 2008.

The extremely narrow spacing between
specific tree rings showed

that a severe drought hit the area
between 1362 and 1392

and then again from 1415 to 1440,

which is more or less the exact time
when Angkor collapsed.

So was there more to it than just
an invasion by a regional rival?

NARRATOR: Founded in 802 C.E.,

the Khmer Empire grew
to cover much of present day

Cambodia, Laos, Thailand
and Vietnam.

It was enormously influential
in the region

and shaped much of its political
and artistic character.

At its peak, the Khmer capital
of Angkor boasted what, to this day,

remains one of the world's
largest religious structures.

Sophisticated urban infrastructure,

as well as a population of
over a million people.

- The city spanned an area
about the size of Los Angeles.

And for comparison's sake, even
an important European city

like London only had a population
of about half a million people

in the late 1600s.

So you can only imagine how
high functioning and well-built

Angkor's infrastructure had to be
to support such a population.

- The infrastructure was centred
around a resource

vital to human survival.

Water.

Because water is as much an asset
as it was a potential threat,

water management was integral
to Khmer culture

and was treated as a religious duty.

Even today, the water that feeds
the agricultural plains

is considered sacred,

and Cambodians bless themselves
with it for good luck.

- It was this very advanced
water management system

that allowed Angkor to grow
to its incredible size.

The city was crisscrossed with
an endless network of canals,

dikes, irrigation
and overflow channels.

An entire river was diverted
into a reservoir.

- All of this water fed
one of the greatest inland fisheries

in the world, the Tonle Sap Lake,

and the land surrounding this lake
is incredibly fertile,

very well-suited for rice crops.

But when you're that reliant
on immense quantities of water,

what happens when it all dries up?

NARRATOR: The researchers conclude
that the years of drought

left the region highly vulnerable
to flooding.

So when the monsoons finally did
return to their regular force,

catastrophic flooding
would have ensued.

- Flooding obviously causes
a lot of problems

for anyone experiencing it.

But how could it have weakened
the Khmer power to such an extent

that they were left on the verge
of collapse

and just needed an invasion
to push them over the edge?

NARRATOR: Archaeologists wondering
how flooding might impact

the urban infrastructure
dig into the soil

underneath the ancient temples.

- The city of Angkor was built
using a very interesting

and advanced technique.

All the city's buildings and temples
were built on an artificial layer

of sand and water.

On top of this, a moat was built
around the temples.

This combination provided enough
support for the huge temples

whilst simultaneously allowing
the moats to collect runoff water

from monsoons.

- But during the drought,

the consistency of this sand
and water foundation changed.

It got weaker.
When the monsoons returned,

the dry earth couldn't absorb
the water fast enough,

and although there were moats
around the temples,

they couldn't handle the runoff.

This caused massive damage
to the urban infrastructure,

while also making it hard,
impossible, to cultivate crops.

- This might have contributed to
a crisis for the Khmer rulers.

When you have collapsing
buildings and bridges,

widespread hunger and then you add
an invasion into the mix.

It's not a surprise that things
didn't go so well for them.

- We know that Angkor returned
to nature after its abandonment.

But what happened
to all those people?

One million people can't
just disappear.

NARRATOR: Just to the south
of the Tonle Sap Lake,

roughly 150 miles
from the ruins of Angkor,

archaeological excavations have been
taking place at a site

known as Longvek,

where the remains of a city
dating to the years

after the collapse of the capital
have been found.

- Longvek was the site
of the Khmer capital

after Angkor was abandoned.

But from what has been found so far,

there weren't many people and
there wasn't much going on here

in the years it was occupied.

NARRATOR: But the farmers working
the rice fields of Longvek

keep unearthing an abundance
of ceramics,

which seems to contradict what
the archaeologists

thought they knew.

- Considering the volume of ceramics

that have been found
in these fields,

it's clear that
a lot of people lived here.

You would need a substantial
population to generate

this kind of volume.

So have we been wrong in our
assumptions about the city?

- It seems like maybe we were.

Some of these ceramics are
truly magnificent.

There's a piece of pottery with
a brown glaze

incised with a coin motif
and good luck symbols.

It used to be the lid of
a ceramic jar,

and it's incredibly rare.

-Very few lids like this have ever
been found outside of China.

In fact, only in Japanese
archaeological sites

dating to
the 16th and 17th centuries

has anything remotely similar
been found.

- So what this indicates
is Longvek's participation

in extensive trade networks
that link China, Japan

and Southeast Asia
in the 16th and 17th centuries.

Having these kinds of things

when you've just been chased out
of your empire's capital,

that's pretty impressive.

NARRATOR: As excavations continue,

archaeologists again and again
discover rare, exquisite pottery.

- There are these green, yellow
and purple glazed dishes

featuring waterfowl on a lotus pond.

This kind of pottery goes
by the very original name

of tri-coloured dishes.

The artwork on here is
truly delicate

and would have required
considerable skill to produce.

- They also date to the same period
as the jar lid,

and coming from southeastern China,

would have been
very, very expensive to acquire.

These ceramics were by no means
meant for everyday use.

They're far too beautiful for that.

They likely would have been
in the possession

of high ranking bureaucrats

or those occupying positions
in the Khmer Court.

NARRATOR: Beginning to question
their assumptions,

archaeologists decide to employ
the use of LIDAR

to survey the area in the hope
they may learn something new.

- Putting it simply,
what LIDAR does

is essentially use a laser
to measure the distance

between the machine emitting
the laser and the ground.

This then creates a very detailed
3D digital map,

which has become an incredible tool
for archaeologists.

- And what these LIDAR scans
reveal is incredible.

A series of earthen embankments
forming an almost three square mile,

rectangular citadel.

Not only was it well built,

but judging by
the wealth of ceramics,

it was thriving economically.

But if the Khmer had seemingly
lost everything

with the abandonment of Angkor,
how could this have been the case?

- Tonle Sap Lake is connected
to a river of the same name

and it drains into the Mekong River,

which is one of the longest
on the Asian continent.

- To this day, the Mekong remains
essential to the economies

and cultures of the
countries it flows through.

And it would have been the same
around 600 years ago.

It connects Cambodia
with central China

roughly 2500 miles to the north.

So you can imagine how many people
would have relied on it for commerce

and how many people
it would have connected,

trading in all kinds
of different commodities.

- By maintaining their capital
close to an essential river

and its tributaries,

the Khmer managed to thrive
despite the incredible pressures

that would have been exerted on them
by invading forces.

NARRATOR: But despite
the Khmer Kingdom's resilience

in the face of powerful
outside forces,

its new capital at Longvek was
eventually sacked

and looted by their long time enemy,
the people of the Ayutthaya Kingdom.

With the collapse of Longvek,

Khmer sovereignty suffered
a serious blow.

The royals were taken into captivity

and what was once a mighty kingdom
was never to rise again

to its past heights.

NARRATOR:
A quarter of a million years ago,

Western Turkey's 2500ft
Cakallar volcano began to erupt.

It sent lava flows cascading down
its slopes,

while ash rained down
thousands of feet from its vent.

- The area where this volcano
field sits today is known as

the Kula region.

And it's fair to say
that this landscape would have been

severely impacted back then.

Thick layers of ash coated the land,
creating a ghostly landscape

that would have terrified both
humans and animals,

forcing them out of the area.

- In terms of a human timescale,
this is a long time ago.

Back then, Homo sapiens,

our ancestors are only found
in Africa,

but Neanderthals, our cousins,

have spread north into Europe
and Asia.

NARRATOR: In 1968,

just a few hundred feet from
the volcano,

workers building an embankment dam
were digging through

the ancient layers of scoria -

dark pocketed volcanic rock

that had been deposited
250,000 years earlier,

when suddenly they observed
abnormal features in the terrain.

- The scoria was lying above
a layer of volcanic ash,

which is what protected
these strange imprints

over the course of thousands
of years.

And it's important to note
that there are little bulges

around the rim of the holes

rising up above the surface
about a centimetre.

This indicates that at the time
they were made,

the ash was wet and coherent,

meaning that these little pockets
were made at the same time

the volcano was erupting.

- The ash layer itself measures
two inches,

while the little oblong pockets
are about an inch in depth.

Some of these features are wider
and longer than others.

While there are also small little
round holes in the hardened ash.

But what are these things?

- Now they could be the result
of ejecta, basically just shrapnel

that comes flying out
of the volcano during the eruption.

But the shapes of the pockets are
far too similar

for that to be the case.

NARRATOR: Each hole has
one or several corresponding

similar sized holes
placed at an angle diagonal to it.

- All of them follow this pattern,
except for the very small holes,

there are four of them,

but each of them is
at a diagonal to the other.

- It may not seem so at first,

but these shapes are
actually very familiar.

We see them all the time
at the beach.

They're footprints!

They're from adults
and from human children.

But also what appear to be some kind
of canid footprints

like a wolf or something like that.

And that's super weird

because humans only domesticated
dogs 40,000 years ago

and this is six times older
than that.

- It seems like these are
footprints of people

or a family of Neanderthals maybe,

possibly running away
from the eruption.

NARRATOR: Since their discovery,

the age of the footprints has
remained a curiosity for scientists

because of the difficulty
in getting an exact date

for when they were created.

- This is because the volcanic rock
in which they were found

is relatively young basalt

and younger basalt is very hard
for geologists to date.

So the assumption has been
that the prints are

hundreds of thousands of years old,
but it hasn't been certain.

NARRATOR: But in 2019, armed with
new state of the art techniques,

scientists decided to reassess
the footprints,

hoping to obtain a more accurate
date for when they were created.

- It's a pretty complicated process,
but two things are measured.

First of all, the decay of
the elements uranium and thorium

creates another element helium.

This helium is present
in little crystals

embedded in the ancient ash.

Second, the radioactive levels
of the element chlorine

can show us just how long
volcanic rocks have been situated

on or near the Earth's surface.

- So this brand new dating technique
tells us something

entirely unexpected.

The volcanic eruption and
the prints are only 4700 years old.

So now the dog footprints
make a lot more sense.

But it means we were off by almost
a quarter of a million years.

And a lot has happened in that time.

- Not only did Neanderthals go
extinct some 40,000 years ago,

but Homo sapiens began spreading
across the face of the earth.

Considering the time scale
we're looking at here,

4500 years ago is quite recent.

It puts us into the Bronze Age.

- So this means that
these footprints aren't Neanderthal,

but human.
Modern human footprints.

Seeing as we were wrong about
the age of these prints

and the species of human
that made them,

it makes you wonder what else
we could have been wrong about.

NARRATOR: Spurred on
by these unexpected finds,

scientists scanned the footprints
using the structure

from motion method.

- The structure from motion method
is a technique

that involves photographing
the object -

in this case, an ancient footprint -
from a few different angles

to create a three dimensional image
of that same object.

- The results are surprising.

The images reveal which direction
the big toe is pointing,

and that, of course, tells you
which way the feet are going.

And it turns out they're going
in the opposite direction

of what we thought.

We'd assumed they were going
away from the volcano,

but this means they were going
from west to east

towards the Cakallar volcano.

- And they were walking
either while the ash was falling

or immediately after.

So it could be that
they were observing the eruption

as they approached the volcano.

- The footprints are also only
about 2.5ft apart,

which indicates
that they were walking

at a relatively relaxed pace.

If they were running, the footprints
would be spaced even further apart.

So they definitely
weren't panicking,

but were rather calmly walking
together towards this volcano

as it was blowing up.

NARRATOR: As the scientists are
working at the site,

local reports emerge of
a discovery of some rock art

a little over a mile from where
the footprints are located.

- The rock art has long been known
by locals

who call the boulder its painted on
bloody rock.

But it's only recently
become known to scientists.

- The boulder is huge,
far bigger than the size of a man,

and it leans out at
a 45 degree angle from the ground.

So it was probably a good place
for shelter from the elements,

whether it was rain or the sun.

DAN:
You can see with your naked eye,

three handprints above a circle
that looks like it's bleeding.

The circle has a bunch of
little dots in it.

- There are also what looks like
four smudges around the circle,

followed by a longer, broader one
at the base of the painting.

That definitely seems
to have faded over time.

Other than the handprints,
what could this represent?

What was their intention?

NARRATOR: In order to enhance
the faded sections of the painting

and obtain a better understanding
for what it might represent,

scientists apply a technique
known as saturation stretching.

- This is basically a process
that uses algorithms

to make the faded areas
more intense in colours,

and that allows them
to digitally reconstruct

what this painting
would have looked like

when it was initially created.

NARRATOR: A much more complete
picture emerges from the rock.

When it was originally painted,

the faded line at the bottom of the
picture was actually thick and bold,

and the remaining lines and
handprints were far more defined.

- The circle now looks like it's
at the top of a triangular shape.

But what's more interesting is
what we thought was may be blood

running down from underneath it.

Considering the location right in
the shadow of the Cakallar volcano,

I wonder if this blood
could actually be lava.

And if this is a depiction of when
it erupted some 4700 years ago.

- It's definitely possible.

The boulder is so close
to the footprints.

And for anyone, let alone a person
living in the Bronze Age,

observing such a natural phenomenon
up close

would inevitably leave
quite the impression.

So what we're looking at here is
maybe their reaction to the event.

- This is pretty special.

Not only does it highlight
the deeply human characteristic

of recording our experiences in art,

but it's also unique
in an archaeological context.

- There are some other examples
of rock art depicting

what appears to be
a volcanic eruption.

But there aren't any this close
to the volcano and to the footprints

the artist may have made on
their way to creating the painting.

NARRATOR: The rock art by the
Cakallar volcano makes it possible

to follow in the footsteps of the
people of the Bronze Age in Turkey,

to walk where they walked,

to imagine what they saw

and realise that the desire to
memorialise such a magnificent event

is what connects us across time.

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