All language subtitles for What.on.Earth.S11E05.1080p.DSCP.WEB-DL.AAC2.0.H.264-BTN_track3_[eng]

NARRATOR:
They're watching you.

More than 6,000 satellites
circle the Earth.

Every day, they uncover
new, mysterious phenomena

that defy explanation.

Revealed from the skies,

the 3,000-year-old code of
the disappeared.

We have to use
these structures to

tell the story
about how they lived.

NARRATOR: The mystery of
the Pennsylvania Terrordome.

What it did was drive
people crazy.

NARRATOR: And Kim Jong's
secret animal assassins.

They'd swim up to an enemy
vessel, and then...

bang!

NARRATOR: Baffling phenomena,
mysteries from space.

What on Earth are they?

Sardinia,

the second largest island
in the Mediterranean.

Kathleen Nicoll
is venturing deep into

this 9,000-square-mile
land mass,

lured by something strange
captured from the skies.

I'm on my way
to investigate a large feature,

and it looks like
it's a castle,

but it's like no other castle
I've seen before.

NARRATOR: The image, captured
on September 27th, 2021,

reveals a strangely-shaped
structure located in

the island's arid interior.

This is a really
intriguing-looking image.

We've got in the center
what seems

to be a triangular tower, then
within it there's this kind of

keyhole-type structure.

This is really very unusual.

I've never seen anything like
it anywhere else in the world.

NARRATOR: A scan of the wider
area deepens the mystery.

NARDI: The island of Sardinia
is littered

with these stone structures.

There are literally
thousands of them

scattered throughout
the island.

NARRATOR: In total,
more than 7,000

towering edifices
are found here.

Locals call them nuraghi,
and they're relics of

an ancient civilization whose
origins and fate

are shrouded in mystery.

AUERBACH: It's inherently
difficult to reconstruct

their lives and their culture,

because they didn't leave
written records.

NICOLL: We don't know much
about these people,

so we have to use these
structures to tell the story

about who these people were
and how they lived.

NARRATOR: The Nuragic
civilization emerges from

this island around
1800 BCE.

Over the following
1,500 years,

they build more than 20,000
of these structures,

a third of which
survive to this day.

Today, Nicoll
is heading to one

concealed in the center of
the island.

Wow.

That's something.

It's actually breathtaking.

NARRATOR:
The crumbling structure sits

on the summit of
a 2,500-foot-high hill

and commands views of a large
region of the countryside.

As Nicoll explores
the central towers,

she discovers their walls
are 10 feet thick.

NICOLL:
This is incredibly impressive.

This wall that I'm standing on
is basically three layers deep.

It has limestone layers that
are built in upon themselves.

NARRATOR: The structure
and others like it

were built
during the Bronze Age.

What sets the Nuragic people
apart is that during this time

most other tribes were
constructing basic settlements

fashioned from mud or wood.

The Nuragics were
master stonemasons,

and they created these
structures without any mortar.

Considering that this is
a civilization that is

4,000 years old,

that's -- that's really
quite impressive.

HUNT: These are
sophisticated buildings.

They're the vanguard of
high civilization.

NARRATOR: In the past,

a number of the towers were
more than 100 feet in height,

making them some of
the tallest prehistoric

structures in Europe,

yet to this day,
their purpose remains unclear.

Nobody knows exactly
for certain,

but the most likely
explanation is that

they're kind of like
mini castles,

each with its own little
territory around it.

NARRATOR:
When the nuraghi are built,

Europe is undergoing
a period of great upheaval

and extreme violence.

Civilizations are swapping
tools and weapons made

from stone with ones
fashioned from metal.

At first,
this transition brings

great prosperity to
the Nuragic civilization.

It seems that Sardinia was
a place of incredible wealth.

The reason for that
was minerals.

AUERBACH:
In terms of natural resources,

this is quite a rich island.

You have copper and tin,
which means that they could

make bronze.

NARRATOR: Over the years,
the Nuragic people

become expert miners
and metal workers.

Word of their skills in
bronze making

spreads throughout Europe.

The Nuragics established
significant trading

partnerships,
and there is some

evidence of metals being
traded as far away

as Scandinavia.

[battle noises]

NARRATOR:
Yet as their wealth grows,

the Nuragic become the targets
for foreign powers

looking to exploit
their mineral-rich lands.

HORTON: When a society controls
valuable commodities,

the civilizations around
the Mediterranean look jealously

upon it and want to control it
for themselves.

It's a time when people were
trying to control the landscape,

so this could be
a fortified tower.

NARRATOR: Other experts
favor different theories,

speculating that
the structures were

used as temples
or observatories.

We still are reaching out
to try to understand,

because the real purpose of
these towers

is a mystery to this day.

NARRATOR: What is known
is that at some point

during the Nuragic reign,
a mystery event hit Sardinia.

Something bad happened.

Whether it was
a snowballing of effects

or whether it was
one sudden cataclysm,

the builders of
the nuraghis

in Sardinia took a pause.

NARRATOR: What's more,
this event has been linked to

one of the most enduring
mysteries of antiquity.

Some have advanced
the idea that

the Nuragic civilization was
the inspiration for Atlantis.

NARRATOR:
Coming up -- tsunamis,

Atlantis,
and the fall of Egypt.

We do know what happened was
inconceivably destructive.

NARRATOR:
And the island of the dead.

It's bizarre -- I mean, this
looks like the island's

been hit by a giant shotgun
round from outer space.

NARRATOR: Drawn by mystery
ancient structures

revealed from the skies,

Kathleen Nicoll is on
the Mediterranean island

of Sardinia.

Wow, look at that.

NARRATOR: The structures,
called nuraghi, are the relics

of a civilization that suffered
a mysterious decline

in the 12th century BCE.

One of the possible
reference points

for the decline is
the legend of Atlantis,

the city buried
beneath the waves.

The Greek philosopher Plato
documents the story

of Atlantis in around
360 BCE.

He writes that,
like the Nuragic people,

it was a highly advanced
civilization whose island is

filled with gates and towers.

After becoming greedy
and morally bankrupt,

the gods punish it with
a cataclysmic event.

HORTON:
The myth of Atlantis has been

a matter of great archaeological
and historical debate.

NARDI: So Plato actually wrote
that there was an island

that succumbed to a massive

marine disaster and was
destroyed in a night and a day.

NARRATOR: The theory goes that
in the 12th century BCE,

a similar event
engulfed Sardinia,

a celestial catastrophe that
destroyed many nuraghi

and gave rise to the legend
of Atlantis.

Some people have suggested
a meteorite coming onto water

and creating a large tsunami

could generate enough force
to impact the coast.

HUNT: If you had a big meteor
land in the water

near the island, yeah,
it could create tsunamis.

There's no question.

NARRATOR: If a giant wave
did once hit Sardinia,

it would likely have engulfed
the low-lying southern part of

the island.

But Nicoll doubts
this is evidence

of the annihilation
described by Plato.

Most of the nuraghi in Sardinia
are in mountaintop areas.

So even if
a tsunami came in,

it probably wouldn't have
completely killed off

the Nuragic people.

NARRATOR: Nicoll heads inland,
searching for more clues

that could shed light

on the fate of
the Nuragic civilization.

Wow.

This is really incredible.

I can see

a triangle surrounded by
a circular court,

and the shape is what you think
of as a keyhole structure.

NARRATOR: The keyhole entrance
guides the geographer down

towards what appears to be
a well.

The walls are getting
narrower as I go down.

This whole place is designed
to draw you into the center.

I can definitely conclude

that this is a sacred place.

NARRATOR: Historians
speculate that this well

was a kind of
subterranean temple,

a place used for ceremonial
worship for many centuries.

Archaeologists found some very
unusual bronze figurines under

the water in the well,

which leads us to believe that
they were some sort of offering

or a way of asking for
assistance from the water gods.

There are cultic associations

with water in Sardinia.

There are goddesses and gods
of springs and water.

NARRATOR: Such was
the importance of water

to the people here that they
construct

40 similar aqueduct temples
across the island.

It would appear that
ritualized activities

take place within them,

because without water,
you can't have life.

NICOLL: Sardinia does not
get very much water,

and it is drought-prone,

so coming here has
deep significance.

NARRATOR: Like the towers
dotting the island,

it is uncertain what took
place within this temple.

But the Nuragics'
deep connection with water

and the ocean could
shed more light

on why they stopped
building their remarkable

stone structures
three millennia ago.

What is interesting
is that in Sardinia

at around the same time,
we see that

many of the sites
are being abandoned, and this

might well be connected to
the Sea Peoples

in the ancient texts.

NARRATOR: The Sea Peoples are
mysterious groups

of naval raiders who begin

attacking different
Mediterranean civilizations

around 1200 BCE.

Some historians speculate
they originated from Sardinia.

The Sea Peoples are recorded
in both Egyptian

and the Mycenaean history
and seem to

have had a massive impact on
both civilizations --

destroyed their towns
and palaces and so forth.

Egyptian inscriptions reveal
that pharaoh Ramesses III

battles the Sea Peoples in
around 1177 BCE.

Some of the invaders
are called Shardana,

a possible ancient name
for Sardinia.

There were whole migrations
of peoples,

and many of them went to
invade Egypt.

NARRATOR: Whether the Nuragic
people sailed from Sardinia

to conquer and occupy other
lands remains unclear.

But over
the following centuries,

their civilization
begins to disintegrate

and ultimately disappears
from history.

NICOLL: We're not exactly sure
what happened to this people.

What's certain is that
the Nuragic civilization was

an amazing,
amazing culture

NARRATOR: Today,
all that remains of

these extraordinary people
are these strange codes

wrought in stone
and visible from the skies.

AUERBACH:
When you think about it,

this is a culture that lasted
for more than 1,000 years,

and it's really
quite impressive.

NARRATOR: Coming up,
inside the chamber of horrors.

It's really shocking to
think that

this was allowed
to happen on U.S. soil.

NARRATOR: And
the disappearing ghost fleet.

These ships vanish completely.

NARRATOR:
July 30th, 2019,

a satellite
flying over the eastern

United States spots
something abnormal

in the Philadelphia suburbs.

What we see are 10 large
individual spokes,

all jutting out of
a central circular point.

So weird,
because you have

this whole urban area,
and then all

of a sudden,
here in the middle of it,

there's this
strange structure.

NARRATOR:
The mystery edifice measures

around 1,000 feet
in diameter.

I mean, it's huge, but you
couldn't really guess

just from looking at it
what this structure is for.

NARRATOR: To some,
the structure's shape suggests

it could be a relic
of a defining time

in 19th century history.

These spokes radiating out
are reminiscent of

a railroad roundhouse with
a rail turntable at its center.

NARRATOR: In the 1860s,
Philadelphia is

a major hub of America's
fastest-growing

railroad network.

Many of
the 230-ton locomotives

have trouble backing up,

necessitating the introduction
of special rotating platforms.

AUERBACH: These were
really a game-changing

piece of technology,

incredibly space-saving
and time-saving, too,

and they became standard
pieces of equipment across

the industrialized world.

NARRATOR: To others,
the presence of a wall

around the structure indicates

that it dates from
a much darker time

in this city's history.

There's a good chance
that these walls

are here to keep
people in.

I believe this is
the notorious Holmesburg Prison.

NARRATOR: Local records
confirm that Holmesburg

opened at this site in 1896.

It represents an attempt to
revolutionize

the U.S. penal system.

Before Holmesburg,
prisons were more like dorms.

There were these big, open
structures where people

could mix.

RODRIGUEZ McROBBIE: Prisons
were more or less these sort of

open stews,
where prisoners of

all different
crimes were lumped together.

The conditions
were unsanitary.

They were really not pleasant
places to be.

NARRATOR: Unlike
traditional prisons,

Holmesburg's layout means that
guards in a central hub

can monitor the 600 cells
at all times.

Designed by
evangelical Quakers,

the isolation of
the inmates is

meant to encourage
penitence and remorse.

This new system
was intended to give

people individual rooms to
think about their crimes,

but unfortunately,
what it basically did

was just kind of drive
people crazy.

NARRATOR: Studies reveal that
such isolation leads to spikes

in psychosis and other mental
disorders among prisoners.

RODRIGUEZ McROBBIE:
Part of the problem came from

a sort of imperfect
understanding of human nature,

one of those things being
that people

do need to be around
other people.

NARRATOR: What's more, many of
Holmesburg's inmates are

violent criminals,

meaning riots, bloody beatings,
and killings are commonplace.

And in the 1950s,
their suffering steps up a gear,

when authorities
hire dermatologist,

Dr. Albert Kligman to treat skin
conditions among the prisoners.

But when Kligman gets a view
of these facilities

and its occupants,
he has some other ideas

about how they could
be utilized.

RUBEN: When Dr. Kligman
sees the inmates,

he's quoted as saying that he
sees acres of skin

on which he can conduct
his medical experiments.

NARRATOR: Outside of prison,
Kligman works for

pharmaceutical companies.

After embedding himself
at Holmesburg,

he begins to test unlicensed
medical products on the inmates

in exchange for money.

These tests help the facility

gain the nickname
the Terrordome.

There are regular reports of
inmates' hair and teeth

falling out, and bandages
conceal evidence of

chemical burns.

SPICER RICE: He's turning these
human beings into animals.

The pain that he's inflicting
upon these people is immense.

RUBEN: Kligman gives the inmates
herpes and staph infections

in order to look
for treatments.

He even administers
radioactive isotopes.

NARRATOR:
Between 1951 and 1974,

Kligman experiments on
thousands of inmates.

In one study, around 70 are
exposed to large amounts

of dioxin,

the highly poisonous component
of Agent Orange.

Many of these men were left

with lifelong
debilitating health conditions.

In fact, to this day,
it's said that you can recognize

a Holmesburg prisoner
because of

the distinctive scars from
skin burns and patch tests.

It's really shocking
to think that this

was not just allowed
to happen on U.S. soil,

but encouraged
and funded by U.S. companies.

NARRATOR: A series of lawsuits
finally brings

the brutal experiments to
an end in 1974.

But despite public outcry,
Kligman escapes sanction.

In the end, nothing
happened to him really.

I mean, he died when he was 93
years old, and in many cases,

revered for discoveries
that he made.

We still use chemicals that he
developed by testing them on

these prisoners many years ago.

NARRATOR: Officials finally
decommission Holmesburg in 1995.

Despite calls for demolition,

the haunting facility
still stands,

a stain on U.S. history,
visible from space.

For many,
this is a disturbing

and harrowing reminder
of some of

the more frightening parts
of our past.

Coming up, Kim Jong Un's
secret subsea assassins.

We're talking about
a power-crazed despot.

So we've got to be
extremely vigilant.

NARRATOR:
And the 100-square-mile cipher.

The dead were so numerous
that they were

stacked up in layers.

NARRATOR:
November 4th, 2021.

Satellites keeping
a watchful eye over

North Korea identify
an unfamiliar object

in a river below.

There's some very unusual
manmade structure floating out

in the river,
maybe anchored in the river.

It looks like there's five
hexagons that are all connected

to each other, and then they're
also connected to the mainland.

It looks like
a strange structure.

NARRATOR:
At 30 feet wide,

each of the shapes
appear to be

enclosures for fish
or other aquatic animals.

Yet the structure's location
puzzles analysts.

KOUROUNIS:
There are naval units located

in close proximity
to this structure,

so that makes me wonder if
somehow the North Korean

military is involved in
whatever is going on here.

NARRATOR:
Analysts turned to Maxar's

SecureWatch technology for
more clues.

It turns out the structure
bears a striking resemblance to

one used by the Russian
military some 4,500 miles away.

These hexagon shapes look
very similar

to this facility
on the Black Sea.

This facility is known for
training dolphins, and this same

hexagon shape is the pen
where the dolphins are kept.

These sites in North Korea

could be where dolphins are
trained for military purposes.

NARRATOR: Over the past
few decades,

dolphins have been used by
several military superpowers

for highly
clandestine missions.

The satellite image
appears to be

evidence that North Korea
is following suit.

There's one thing you can rely
on, is that no matter how dire

and perilous the state of
North Korea's economy is,

its leader will always ensure
that its weapons

technology grows.

The use of dolphins in naval
missions begins in 1960,

when U.S. researchers study
the animals to streamline

torpedo design.

But they soon realize that
the highly intelligent mammals

can play a much more direct
role in warfare.

The U.S. Navy has conducted
a lot of research

and experimentation using
dolphins for non-combat roles,

to sort of achieved
tactical and operational

objectives that simply
can't be done by humans.

NARRATOR: In the first
open sea exercises,

a dolphin named Tuffy
successfully relays equipment

to divers 200 feet
below the surface.

In further tests,
the Navy uses

the mammals to detect and
identify underwater explosives.

Their sonar is extremely
sensitive, and it gives them

an acoustic picture of what
the environment looks like.

This allows them to travel
through murky waters

and locate mines on the sea
floor or at the surface.

NARRATOR: In response,
the Soviets also

begin assembling units of
military dolphins.

Former Communist dolphin
trainers claim the mammals

were kept in small,
isolated pens,

like the ones seen
in North Korea

and deprived of food to make
them reliant on their handlers.

MUNOZ:
The Russians actually tried

to weaponize these animals,

trying to use dolphins
as a method of carrying

either munitions or bombs
and using them to

attack adversaries

in actual combat operations.

WALTERS: They'd swim up to
an enemy vessel,

rub against the keel,
and then...

bang goes the dolphin
and the target.

NARRATOR: In more recent years,
Russian dolphins have

been trained to carry out
stealthier missions.

Fitted with a lethal
gas-filled needle,

they patrol Russian naval
facilities to

track down and inject
enemy divers.

As far as we can tell,
these troubling

dolphin training programs are
still up and running.

If anything,
they're probably more advanced

and secretive
than they were before.

If North Korea is acquiring
and training the animals,

that is a real cause
for concern.

NARRATOR: North Korea possesses
40 nuclear weapons,

which can be launched
from submarines.

The fear is that
Kim Jong Un will use

these animals to prevent
Western nations from monitoring

their deployment.

Historically,
Kim Jong Un has

been deeply mistrustful of
foreign powers.

So he could have trained
dolphins to try to take out

any vessels or divers that could
have come close

to his nuclear arsenal.

NARRATOR:
North Korea has a history of

such preemptive strikes
against naval adversaries.

In 2010,
a mysterious blast sinks

the South Korean Navy ship
Cheonan, killing 46 sailors.

The facility is seen from
space could represent

an unusual and worrying
escalation in tensions

with Kim Jong Un's regime.

We're talking about
a totalitarian state,

and it's ruled by this kind of
power-crazed despot.

So we've got to be extremely
vigilant about North Korea.

NARRATOR:
Coming up,

the 400-foot-long
floating skeletons.

You'll have the predators
come in and strip it

down to its bones.

NARRATOR: And attack
of the cannibal army.

MUNOZ:
I mean, can you imagine?

It's like something
out of a nightmare.

NARRATOR:
May 29th, 2020.

Satellites wheeling
over the West African

city of Nouadhibou

scan the coastal waters below.

At first glance,
it doesn't seem that strange,

a bunch of ships off
the shore,

except I'm not seeing any
wakes behind them.

These ships don't seem to be
moving, and a lot of

them don't look like they're
in a very good state of repair.

NARRATOR: Historic images
confirm around 300 vessels,

many of them hundreds
of feet long,

have lain abandoned for years
or run aground.

The fact that they're just
sitting here idly is

pretty puzzling.

RUBEN: Ships can cost millions
of dollars.

It's strange that all
these vessels would

just be left there to rust.

NARRATOR: Nautical records
reveal that the ghost fleet

is the legacy of a saga

of corruption that has
blighted this city for decades.

Unfortunately,
over the years,

Nouadhibou has become
the world's largest

ship graveyard.

This is basically
a time capsule

of rusting vessels
from across the globe.

NARRATOR: Globally,
shipyards break up around

800 large vessels each year.

The biggest facilities strip
up to 10 million tons of

steel annually,

166 times the amount found in
the Empire State Building.

Just because a ship is
decrepit and rusted

and derelict doesn't mean that

it doesn't have tremendous
value in the raw resources

that are still there.

RUBEN: Everything that can be
salvaged will be salvaged.

These ships vanish completely.

NARRATOR: Ship breaking can
generate billions of dollars for

yard owners.

The potential for vast
riches means

there's a dark side to
the industry.

Until about the late
20th century,

these scrapyards would
typically be in cities

in industrialized nations,

but with labor being very
inexpensive in certain

countries and the cost
of steel going up,

it's been more economical for
these shipbreaking yards to be

in places like Africa
and Bangladesh.

Work in these shipbreaking
yards is incredibly dangerous

and is usually performed by
migrant workers

who have no choice but to work
in these unsafe conditions

or face hunger
and homelessness.

NARRATOR: In some yards,
exploitation is rife.

There are
no safety regulations,

and children account for up
to 20 percent of the workforce.

It's not uncommon for these
workers to have all kinds

of injuries,
from being crushed

by equipment
to broken limbs to

burns from their blowtorches,
you name it.

NARRATOR: Since 2009,
more than 400 people have

died while dismantling vessels
in these yards.

Other workers face different
but equally horrific fates.

Even if these workers leave
the job site alive,

they're still in contact with
so much hazardous waste that

they can be made sick
by what they work on.

RODRIGUEZ McROBBIE: People
who work in these places

often succumb to horrible
cancers or even diseases like

asbestosis later on in life.

NARRATOR: Despite the toxic,
perilous conditions

at these yards,
owners must pay large sums

to have their vessels
dismantled there.

This has lured ships to end
their days at the site

in the image.

It's really expensive to
dismantle the ship properly

if you want to do it.

Many owners of these vessels
simply can't be bothered.

The solution --
dump them here.

Countries like Mauritania
have very depressed economies.

Money is hard to come by.

So it can be very tempting
for these officials to take

these bribes to basically

allow their waters
to become a dumping

ground for these ships.

NARRATOR:
Over the past 40 years,

Nouadhibou has become
the global center

for illegal shipbreaking.

Once dumped in the bay,

each vessel is scavenged by
swarms of workers

and every morsel sold
for profit.

There's value not just in
the raw steel, but in things

like the fittings,
the windows,

the cutlery,
the life preservers.

This totally reminds me of

a carcass left in the woods
to decompose.

You'll have the predators
come in and strip it

down to its bones,
and eventually,

there'll be nothing left.

NARRATOR:
As the ships are picked apart,

they release
a toxic cocktail

of carcinogens
and heavy metals.

These ships are often smeared
with paint and oils that seep

out into the ocean,
polluting the ecosystem

and harming local wildlife.

The waters around here have
become so noxious that

they can change the sex of
local sea creatures.

Untold amounts of oil leak
from rusting tankers,

polluting local beaches
and bays.

At first, abandoning
these vessels seems like

a victimless crime,

but in the long run, all of
these toxins ending up in

the environment becomes a real
ecological catastrophe.

NARRATOR: While officials
continue to line their pockets,

those who live here will keep
paying with their lives.

The legacy of the abandonment
of these ships

is going to last
for generations.

NARRATOR: Coming up,

death in paradise.

Something pretty horrific
happened here

on the sleepy island of Tonga.

NARRATOR:
June 27th, 2020.

Aerial archaeologists study
the Pacific archipelago

of Tonga.

As they analyze Lidar scans
of the island of Tongatapu,

they spot something strange

hidden beneath
the forest canopy.

CAVELL: You see these weird
circular marks all over

the island, and there are
thousands of them.

AUERBACH: It's bizarre --
I mean, this Lidar scan makes it

look like the island's been hit
by a giant shotgun round

from outer space.

NARRATOR: Around 10,000 circular
shapes litter the land mass,

relics, some suspect,
of a wave of

violence that swept these
islands eight decades ago.

WALTERS: The Lidar scan,

if you look at it,
your mind turns to

one thing -- bombs --
and that, of course, means war.

ANNOUNCER:
The crime of the century.

NARRATOR:
In January 1942,

following the attack on
Pearl Harbor,

Japan sets its sights on
several strategically vital

South Pacific Islands.

The Second World War was
actually the world's first

truly global conflict,
and as a result,

it even makes its way to
the relative obscurity of Tonga.

[gunfire blasting]

NARRATOR: As Japanese forces
sweep towards the islands,

the U.S. launches
a counteroffensive.

In May 1942,

the two nations face off in
the Battle of the Coral Sea.

The engagement sees Japan
capture territory in

New Guinea
and the Solomon Islands,

while U.S. forces seize Tonga.

Tonga's main island became

a major transport hub for
the Allied shipping lanes.

It was key to the U.S. strategy
in the Pacific theater.

NARRATOR: What's puzzling about
the image is that America's

8,000-strong occupying force

ensures Tonga emerges
unscathed from the war.

It appears that the American
military occupation

functioned as a deterrent,

because the Japanese never
attacked the island.

And that produces a bigger
question -- if warfare

never came to Tonga during
World War II,

what are all these pockmarks?

NARRATOR: Studying the image
in more detail gives

a new perspective on
the strange circles.

AUERBACH: When you look
a little bit closer,

you see that these
are not concave.

They're actually convex.

They are small mounds or
raised bits of earth.

What these look like to me
are burial mounds.

NARRATOR: Archaeological
examinations confirm

the presence of cadavers
in the mounds.

Some contain over 100 bodies
and appear

to have been used for
internment for centuries.

They're actually constructed
over an extraordinarily long

period of time, and the fact
that these mounds are spread

evenly all over the island
suggests that what we are

seeing here is some sort of
ritual burial practice.

When European explorers first
visit Tonga in the 1600s,

they find an island divided
between rivaling chiefdoms.

The tribes use the mounds in
the image to bury their dead,

but analysis of
the distribution of

the graves uncovers
a strange anomaly.

What we see on the eastern
part of the island is an area

that was relatively
underpopulated,

and yet there are
a huge number of

these mounds in the region.

AUERBACH: There are
a staggering number of them,

which means something pretty
horrific happened here on

the sleepy island of Tonga.

NARRATOR: Accounts
from missionaries who visited

the island could help explain
the mystery.

There's a clue as to why
so many deaths appear to have

taken place in just

one part of the island,
and that comes from this really

bloody chapter
in the island's history --

the battle of Poha.

NARRATOR: At the turn
of the 19th century,

Tonga is gripped
by a civil war

between its most
powerful chiefs.

In the year 1801,
the warlord Vaha'i

moves his warriors
eastwards across the island,

intent on attacking his rival.

The reason for the western
chief invading was that

the eastern tribes

had been involved in
the assassination

of the Tongan king.

The chief Vaha'i was on
a revenge mission,

and he was not taking
any prisoners.

MUNOZ: People were
massacred left and right.

The dead were so numerous
that they were

laid up across each other in
large piles.

There are also accounts that
go a step further that discuss

the creation of great pyres,

where bodies of the slain were
roasted, with the implication

being that cannibalism
happened afterwards.

NARRATOR: After being piled
high in mounds all over

the battlefield,

the slain are claimed by
the earth.

MUNOZ: The extreme death toll
suffered in the east of

the island could explain why
the area has more mounds

than elsewhere.

NARRATOR:
Over the following centuries,

the warriors' tombs are covered
in vegetation,

only to be revealed
once more from the skies.

These burial mounds show us
that no part in human history

is free from evidence
of man's capability

of violence and cruelty.

Man is truly wolf unto man.