COLIN: Ireland, a small island on the edge of Europe.

Between the old world and the new.

As an island nation, the sea is part of who we are.

The sea has allowed us to leave and it also has allowed us to come back.

And that really is the history of the Irish.

COLIN: These seas were not barriers.

These were our highways, charting the ebb and flow of an island people.

The landscape itself bears the traces of our history.

There were dairy farmers who came here shortly after 4000 BC.

COLIN: And the people who are the Irish.

How and when did we become who we are?

People were in tune with the changing seasons and the differences in light.

MARY: I can't think of any other name that towers across Europe like the name of Columbanus.

COLIN: The Irish have been saints and scholars, poets and storytellers, soldiers and sailors.

IGOR: This was a very big market for sailors.

Some of them were Irish and especially from Galway.

COLIN: The history of the Irish has long been a global one.

JANE: An Irishman called Gerald Aungier, he's the founding father of Bombay.

COLIN: Many came to these shores.

Many left, never to return.

This is arguably the largest Irish graveyard on the entire planet.

Today, over 80 million people worldwide say that they are Irish.

The Irish became kinds of Irish gauchos here in the Pampas.

KEVIN: Have the Irish left a legacy in the Caribbean?

You've just got to open a phone book, look at the names, and there they are.

COLIN: From that Small Island: The Story of the Irish tells the fascinating history of an island people who have truly left their mark on the world.

COLIN: The story of Ireland's prehistory is still unfolding.

Deep underground, a team of archaeologists are searching for evidence that could unlock the secrets of our earliest people.

So here you can see a series of layers in the cave.

These are sediments in the cave system.

As we follow along my trail here, there you can see a bone, possibly of a carnivore from the Ice Age period embedded within that white material.

But we're obviously excited to think, could we find DNA of early humans, whether that be Homo sapiens or even earlier, even Neanderthals, you know, we don't know.

So it's all up for grabs at the moment.

COLIN: Ireland was already an island thousands of years before Britain finally separated from mainland Europe.

This meant that the first settlers, the people known as hunter gatherers, would have arrived by boat.

It's always the sea.

It's the sea, the sea, the sea.

And I think sometimes we as island people have forgotten that and how important travel by sea was in the past.

Over the last 20 or 30 years, we have a tremendous richness and diversity of archaeological evidence.

And that has allowed us to build a very coherent and comprehensive picture.

Still with lots of question marks about prehistory.

The first ancient human genome came out about 2010.

The field has completely exploded in the past decade or so.

Irish hunter gatherer genomes, they are part of the same broad population grouping, Western hunter gatherers.

We see the same mutations involved in blue eye colour, but none of the mutations we associate with light skin today.

So we get this sort of prediction of quite an unusual physical appearance, dark skin and the bright eyes.

COLIN: These first Irish settlers lived off the land, fishing, foraging and hunting small game.

Like similar groups in Britain and Europe, they belonged to a population type which genetically no longer exists.

They lived here for 4,000 years before they disappeared into the mists of time and a new population reached these shores.

These new people were Ireland's first farmers.

And this is a remarkable phase of the human past, where cattle, sheep, goats, pigs are domesticated.

Barley, wheat are domesticated along with other valuable food plants.

Now, that changes life utterly.

It leads to more condensed, populist societies and this new technology is successful.

JESSICA: That's a big deal for the island of Ireland, actually, because we don't have any native wild predecessors of the domesticates like cattle, sheep and goats and like wheat and barley.

So those domesticated resources had to have been physically brought over the sea by people in boats.

That suggests you have a very determined group or groups of people who really do want to put down roots on this island.

COLIN: Among these first farmers was a young woman whose skeletal remains were found near Belfast and County Antrim.

She would become known as as Ballynahatty Woman.

When we sequenced her, it was the first ancient Neolithic genome sequenced from the British Isles.

And we found that she had this Anatolian ancestry.

So we were able to infer just from one genome that when farming came here, it came here with people.

COLIN: On the edge of the Atlantic, on the rugged North Mayo coast, lies Céide Fields, one of the largest and most important Neolithic field systems in the world.

SEAMAS: There were dairy farmers who came here shortly after 4000 BC.

In terms of world history, what we have here is an exceptionally early example of structuring the land into fields and controlled agriculture, if you like.

Underneath this vast area is a complete system of fields laid out by our first farmers and marked by stone walls.

They remained hidden for thousands of years by the bog which grew over them.

SEAMAS: I grew up a couple of hundred yards from here, and my father, Patrick Caulfield, when he was cutting turf in the 1930s on our own bog just over few hundred yards from here, he noticed lines of stones.

And he recognised that he wasn't an archaeologist, but that they had to be older than the bog, therefore very ancient.

NARRATION: "When he stripped off blanket bog The soft-piled centuries Fell open like a glib; A landscape fossilised, Its stone wall patternings Repeated before our eyes In the stone walls of Mayo."

[cows mooing] JESSICA: The island of Ireland from the get go has a very strong relationship with dairying and dairy products.

You see that relationship with milking, with dairying persist in Ireland over time.

At least some of those cows were used for pulling heavy loads.

To move timber, to move manure around fields, for example.

Big stones, you know, to build megalith monuments.

Sometimes movement of stones that were several tonnes in weight.

That's a pretty big statement.

COLIN: These statements in stone still dominate Ireland's landscape.

These tombs, evidence of a highly developed culture, allow us an insight into the humanity of these early people.

Some of the earliest human remains we have from the farming period in Ireland come from Poulnabrone Portal Tomb in the Burren.

And we sequenced a population of individuals from that site.

We had one result that was quite touching, I suppose.

We found one of the infants buried there had three copies of chromosome 21, which is the cause of down syndrome.

When we looked at the isotopic data of this individual, he also had a signature of being breastfed.

So he was being looked after, but obviously passed away when he was an infant.

GABRIEL: How do we... discover the humanity of people in prehistory?

Our most direct source of evidence are human remains.

Because this concern about... celebrating, remembering the dead is something that runs through in different ways, runs through prehistoric societies.

COLIN: The most famous megalithic sites in Ireland are found at Brú na Bóinne.

The rich ritual landscape on the banks of the River Boyne and a UNESCO World Heritage site.

They include Knowth, Dowth and Newgrange.

JESSICA: In terms of time periods for a monument like Newgrange, the common two sites they're usually used as indices are Stonehenge in southern Britain and the pyramids of Egypt.

So Newgrange and similar developed passage tombs are at least a thousand to two thousand years earlier than this.

You have to remember these people were farmers predominantly.

But clearly the level of precision and the level of kind of observation, almost hyper observation of their environment.

I think this monument itself tells us how keenly people observed their environment and were in tune with the changing seasons and the differences in light.

COLIN: Newgrange was designed to mark the turning of the year through its alignment with the winter solstice.

This is the shortest day, but it means that everything after this day is getting longer and the light is coming back.

So it's, it's an exciting time, it's a happy time.

And I think that holds through the millennia.

COLIN: The civilisation that produced the enigmatic wonder of Newgrange would itself come to an end, as, yet again, new peoples found their way to Irish shores.

DANIEL: I think one of the most dramatic, and unexpected findings in European ancient DNA, is the one that in the third millennium BC, a very large migration, a massive migration took place from the Steppe Region, swept into northern Europe and also, didn't replace but profoundly changed all the populations of northern Europe.

LARA: These people, these pastoralists coming in, they might have also had a technological advantage, an advantage in mobility and warfare.

And it seems like they had the domestic horse, things like that.

DANIEL: It does correlate with cultural change, including at one stage with metal with the Bronze Age.

The population changes to the tune of about 90 percent, which is huge.

COLIN: An excavation on Rathlin island off the Antrim coast led to the discovery of three Bronze Age skeletons.

One of them would shed new light on the people who had now arrived on these shores.

Well, I suppose for me, archaeology, it's all about people.

And you know, when I'm laying this person out, like I see a skeleton, but I'm always trying to look at what that person was like in life.

He was potentially a brother, father, son.

We reckon he's probably about 40 to 60.

So he would have been a good age, you know, for a prehistoric person, he would have been about 5 foot 11.

And his genetics are similar to other contemporary people.

And they seem to have been part of a wave of people from the, what we call Pontic Steppe, so over in Russia and Ukraine and they seem to have moved westwards.

So it's really interesting that they got as far as Ireland.

We know he was lactose tolerant and he carried a marker for haemochromatosis, which is a condition that affects a lot of modern Irish people.

COLIN: New technologies, including analysis of ancient DNA now allow us to digitally reconstruct faces from the deep past with scientific accuracy and come face to face with Rathlin Man.

EILEEN: This is a world-renowned lab where they're undertaking a huge amount of scientific research in facial identification and reconstruction.

I'm really excited because, you know, I've obviously studied this individual's skeleton, so I'm really curious now to see what the science tells us that he looked like.

So this is the first time you're seeing a face.

-Mm-hmm.

-So I will click play.

Okay.

Here we've got the skull, we re-articulated the mandible and then we rebuild the face where it's missing parts.

Such a sense of anticipation.

So here we have the eyeballs in the anatomical position.

And here we have the tissue duct pegs.

And here you can see the muscles to indicate the shape.

And then you see the shape of the head.

EILEEN: Oh, it looks fabulous.

No, no, he looks incredible.

And it's, you know, it's what I would have imagined him, you know, as somebody of, you know, fairly high social standing in his community.

You know, he has that, that look about him.

Walking down the street in Rathlin Island, he would just look like one of the local people.

I mean, this man lived 4,000 years ago.

And we know as well there's genetic continuity with people from Ireland and Scotland.

So, you know, we're looking at an ancestor.

COLIN: Ireland in the Iron Age was a highly organised society based on a warrior aristocracy.

The Irish were by now speaking a Celtic language, the precursor to Irish.

They had their own rituals and religious practices.

They had kings, queens and druids.

Royal sights commanded the landscape.

And at the centre, the Hill of Tara, seat of the high kings of Ireland.

Here we have generation after generation, all the history of Ireland from Neolithic through even to the modern period.

Located on the top of a small hill with a magnificent view.

Deliberately, because the King of Tara was regarded as the king of the world and this was the centre of the world, the axis mundi.

COLIN: The royal sites occupy an important place in both history and mythology.

They were the inspiration for Ireland's most famous heroic tales.

PATRICK: Navan, like many places across the island of Ireland, is an incredibly storied place.

It's the backdrop for a huge number of Ireland's most important and famous stories.

Of course, the Táin Bó Cúailnge and all those, those famous figures, some of the earliest vernacular literature in Europe.

NARRATION: "Beautiful indeed was the youth who thus came to display his form to the host, namely Cú Chulainn Mac Súaltam.

In the chariot beside him was a long shining edged spear.

In one hand he held nine heads, in the other ten, and these he brandished at the hosts.

Those were the trophies of one night's fighting by Cú Chulainn."

DAVID: Irish literature is the first big vernacular literature after the Greek and Roman literature.

And it takes it an enormously important position in European literature.

But also compared with other literatures across the world, in a sense, these Irish tales occupy a similar position in the cultural heritage, like the Iliad or the Odyssey do for the Greek or Roman Literature.

[ominous music] COLIN: In the 1st century BC a new world power came to the fore, the Roman Empire, which would stretch from Europe to North Africa.

The Romans conquered Britain in 43 AD.

Ireland, however, was never invaded.

Quite a few textbooks of Irish history start with the fact that Ireland was never part of the Roman Empire.

And because it was an island, it managed to kind of stand outside this great, you know, powerhouse that existed.

But it was deeply influenced by its contact with the Roman Empire.

And we can see that really from the first century AD through trade contacts between Ireland and the Roman Empire, we have Roman writers commenting on affairs in Ireland.

There's this kind of curiosity at this place that lay beyond the boundaries of empire, sometimes with a bit of fear and suspicion, but there was always an awareness of Ireland.

You know, just across the seaway.

ROY: We do have accounts of Ireland written by Romans.

Probably one of the more famous accounts from the first century AD is by the geographer Strabo, who gives us the first ethnographic account of the Irish.

It's not a very flattering one.

NARRATION: "Concerning this island, I have nothing certain to report except that the people living there are more savage than the Britons, being cannibals as well as gluttons."

Strabo says that his information doesn't come from any reliable source, that it's all hearsay.

And the people that he heard these rumours from have no direct experience with Ireland whatsoever.

So he himself casts doubt on these accounts.

COLIN: Although never conquered or invaded, Ireland had connections with the Roman world, as was well known to sailors and merchants.

The geographer Ptolemy based his famous map of Ireland on their accounts.

ROY: Ptolemy gives us coordinates from which we can draw a map of Ireland.

Those coordinates are accompanied by place names and names of rivers and names of peoples.

They would all be on Ptolemy's map.

COLIN: Roman Britain would suffer raiding by the Irish throughout the third and fourth centuries.

The Irish would also settle in parts of Britain, leaving traces of their language inscribed on stone monuments known as Ogham stones.

DAVID: There are about 400 known Ogham stones from Ireland, almost all of them in the south.

Ogham stones are the earliest type of inscription that we have from Ireland and the earliest type of evidence that we have in written form of the Irish language.

So Ogham is an alphabet.

In its original form, it consists of 20 letters.

They're quite unusual in the sense that the inscriptions, not like we would normally do, we would write on the face of a stone.

But Ogham inscriptions are written on the edge, on what we call the iris of a stone.

Ogham is an ingenious writing system as to the contents Oghams don't contain personal names, usually the name of a man and his father or his grandfather or the wider kin group to which the person belonged.

COLIN: The Roman Empire was coming under increased pressure from all sides.

The pressure was particularly intense in those provinces located on the edges of the empire, including Britain.

CLARE: What we get records of from the late 4th century is the empire is starting to crumble.

And as that happens, it obviously creates political opportunities and this power vacuum emerges and we start to get references of raiders from Ireland attacking Britain.

COLIN: Many slaves were taken in these raids back and forth across the Irish Sea.

One in particular would leave an indelible mark on the history of Ireland.

His name was Patrick.

Despite not being born on the island, he would come to represent the very essence of what it meant to be Irish.

ROY: St Patrick was a member of the Romano British aristocracy and he was raised, or he would have been raised in a town very much like this.

We are very lucky in that we do have two texts written by St Patrick's own hand which has survived into the modern world.

And one of these is his text, the Confessio, which Patrick wrote as a sort of justification and defence of his missionary work in Ireland.

Ego patricios peccator rustic... Translated: My name is Patrick, so I am first of all a simple country person, refugee and unlearned.

I was taken into captivity in Ireland, along with thousands of others.

They were pagans and I hoped they might come to faith in Jesus Christ.

COLIN: Patrick's life was soon woven into the many stories and myths that envelop his memory.

Already by the seventh century, we've got the Life of St.

Patrick by Muirchu, where St.

Patrick is this miracle working druid defeating wizard almost.

You know, he's able to kind of, you know, dispel snow on the landscape.

He's able to defeat pagan fire, and he's much more this kind of almost superhero character.

COLIN: The Irish took to the new religion with fervour, with many of the kings and the learnt classes becoming Christian.

While old beliefs might have lingered, they were very much in the background.

CLARE: The way that Christianity embedded itself within Irish culture and landscape is very cleverly thought out because it didn't necessarily come through confrontation, but through adaptation.

Croagh Patrick is, is one example of a mountain in the Irish landscape which has now become a centre of pilgrimage.

There's the tale that, you know, St.

Patrick expels the snakes from Ireland whilst he's on Croagh Patrick as well.

So those stories still live with us as part of contemporary Irish culture.

COLIN: The cult of local saints was a central feature in establishing Christianity in Ireland.

Three were pre-eminent: Patrick, Colmcille and Brigid.

CLARE: St Brigid's cult is very interesting because there's a debate as to whether St.

Brigid was originally a goddess who then became transmuted into a Christian saint.

But then we also have early narratives about Brigid as a real woman who was venerated for her piety and is a founder of a religious community.

And I don't suppose we'll ever know for sure which of the stories is true, but certainly that the early date of the early writings around St.

Brigid suggest that she was a real individual.

"Encipit vita sancte.

Translated: Here begins the life of Holy Brigid, the Virgin, whose feast day is the 1st of February."

COLIN: Colmcille would spend much of his life away from Ireland, on the island of Iona, off the west coast of Scotland.

Here he founded one of the most important and influential monasteries in Christendom.

Iona is arguably the single most important church in these islands.

In the period between the mid 6th and the mid 7th century, there's an amazing amount of material is produced by Iona scholars in Irish and in Latin in the period from its foundation.

COLIN: Iona would also be instrumental in spreading Christianity throughout Britain.

[church bell tolls] Aidan, an Irish monk from Iona, established the famous monastery at Lindisfarne on the Northumbrian coast.

CLARE: England was only partially converted at the time when Aidan and his companions arrived and Lindisfarne became a really important ecclesiastical centre in the area, sending out missionaries to other parts of England.

The Irish monks that came here had a huge influence on religion in England, so this site soon became very important as a centre of learning and monasticism and it became as a renowned centre for scholarship.

So the Lindisfarne Gospels were produced here, which is a very high status manuscript of the Gospels, beautifully illustrated, that was made around the turn of the 8th century.

COLIN: Ireland itself was now an island famed for its monasteries and learning.

These shores attracted students from across Europe, with one English writer telling of boatloads of Englishmen going to Ireland to study.

The sons of noblemen and clerics were travelling to Ireland in search of education as well as spiritual enlightenment.

And it really helped solidify this reputation of Ireland as an island of saints and scholars.

COLIN: The Irish monks and scholars wrote superbly in Latin, but they didn't ignore their own language and traditions.

It's about the 7th century or so.

That somebody must have made the connection that you can actually start writing your own language, your own native language in the Latin Alphabet.

And that's where the real big written tradition of Irish starts.

DÁIBHÍ: The amount of literature in Latin that is produced in this country or by Irish scholars who were taught in this country is far in advance of all the other countries in Western Europe put together.

They also learnt it in the native language in Old Irish, for example.

And we have a massive amount of literature from the early period.

COLIN: One particular characteristic of Irish monks of the period, which would lead to their presence far beyond their native shores, was their willingness to leave Ireland in an act of self sacrifice for their faith.

DÁIBHÍ: One of the things that's invariably associated with the Irish is this idea of wandering, wanderlust, Peregrinatio, as it's called Latin.

And the Irish are the Peregrini, the Scotti Peregrini, the wandering Irish.

And there certainly does seem to be an element of self imposed exile, I suppose, on the Irish from an early period.

They understand this idea of individual saints, the saints of the Western Desert, St Anthony and St Paul and so on, taking themselves away from Roman civilisation, taking themselves out into the desert and, and occupying themselves solely with consciousness, contemplation of God.

And therefore the only way they could do that is by imagining a desert for themselves.

But in their case, the sea is the desert.

It's not the sand, it's the sea.

Because the sea is all around them.

(NARRATION IN GAELIC) NARRATION: "There is a grey eye that backward looks and gazes.

Never will it see again.

Ireland's women, Ireland's men."

COLIN: These monks left their mark in some of the most inhospitable locations imaginable.

The most famous, the awe inspiring jagged rock of Skellig Michael, seven miles off the south-west coast.

DÁIBHÍ: The Skelligs are such a phenomenon in geophysical terms, I suppose they're just an amazing sight.

So close to the elements.

You know, you're, you're the next stop is heaven.

COLIN: The beginning of the seventh century, during what some would call the Dark Ages, Europe was a continent ravaged by war and conflict after the final collapse of the Roman Empire.

Irish monks and scholars would bring their faith and their scholarship with them as they journeyed throughout Europe.

Among the most famous was Columbanus.

MARY: We're in a rather remote but very beautiful part of northern Italy.

We're in the magnificent village of Bobbio.

And it got its name and it got its fame from an Irishman who came here 1500 years ago and died here.

St.

Columbanus.

By the time he came to Europe in his 40s, he was one of Ireland's outstanding scholars.

He was one of Europe's outstanding scholars.

DÁIBHÍ: We know of him in the same way almost as we know of St.

Patrick, because he has left some writings, very few, relatively speaking, but those that have survived are quite extraordinary.

COLIN: "The freedom of my country's customs, to put it so, has been part cause of my audacity.

For among us, it is not a man's station, but his principles that matter."

The character, the personality that comes through in the letters is really quite extraordinary.

He may not have been the most straightforward of individuals.

You might not have liked to meet him, you might not have liked to be a member of his community.

But you couldn't doubt his sincerity.

You know, the letters really do strike you as somebody who's quite exceptional.

MARY: He died in the early part of the seventh century.

But a thousand years later, the impact he had was so profound, his legacy so rich, that they build this magnificent basilica in his name and they take his body from what would have been a very, very modest grave and his body is moved here.

COLIN: The legacy of Columbanus would be long lived.

In the aftermath of the Second World War, Europe needed a new vision more than ever.

MARY: We just had two world wars.

Europe has been a killing field for millions and people are tearing their hair out saying, is this always going to be the future?

Have we nothing else to offer each other except perpetual enmity and war?

And four men from an intellectual tradition in Europe in which the story of Columbanus, the thinking, the talking of Columbanus is embedded.

They put their heads together and they say, "We've got to do something better than this."

They go back to the life of Columbanus.

These are the fore fathers of what we call today the European Union.

COLIN: Irish monks and scribes would leave a lasting legacy in Europe.

Some of the most famous and most precious of early mediaeval manuscripts were created by these Irish saints and scholars.

IMMO: We are in the city of St Gallen, modern day Switzerland.

It gets its name from the Irish Saint Gallus, who was one of the companion of the famous Columbanus.

The monastery of Saint Gall picked up massively in the 8th century and a beautiful library was created with amazing Irish manuscripts that we can still see housed here.

This a gospel book that is, it's dated at around 800.

It's the gospel of John.

The Gospel of the John was particularly revered among the Irish.

What you can see here is ornamentation on the page that is very similar to what we have in our famous books at home.

And this one here will have survived because it is so beautiful to look at.

COLIN: The earliest examples of Old Irish are to be found written in the margins of manuscripts preserved here.

They give us a remarkable insight into the humour and humanity of these Irish monks, toiling in their scriptoria far away from home.

And this is where you then see either interesting remarks about the terrible ink that they were using, the terrible shape that they were in after a long previous night of boozing, I suppose.

COLIN: In the margin of a manuscript on Latin grammar, we find an inscription written in Ogham's script that reads Latheirt, meaning excessive drinking or hangover.

This hungover scribe was able to lament his state while keeping the knowledge safe from the prying eyes of anyone other than his fellow Irish.

The Irish monks did not confine themselves solely to the gospel books for which they were renowned.

IMMO: The Irish were at the forefront of mathematics and astronomical art in the early Middle Ages.

And many of their texts are still hidden in continental copies.

And we'll browse the libraries of Europe in search for those lost texts.

COLIN: One such library is located in a Benedictine monastery high in the Alps.

[choral singing] IMMO: I first came to Einsiedeln in 2006 looking for texts written by Irish monks in the early Middle Ages on astronomy and mathematics.

This text, this was written by an Irish scholar at around 700.

It is an amazing find on various levels.

And this is the oldest textbook on the reckoning of time, with a very strong mathematical and astronomical basis that exists.

So this is the founding text of a monastic discipline that was there throughout the Middle Ages, where the Irish were instrumental in creating this discipline, and then from scratch, designed a new landscape of knowledge.

COLIN: In Ireland, artistic production was also flourishing.

This golden age, as it became known, has left us artefacts of world renown.

MAEVE: With the coming of Christianity, a whole new range of objects were required in the service of the church.

And probably the best example we have surviving from Ireland is the Ardagh Chalice.

This 8th century object is, you know, one of the most important in terms of achievements for Irish civilisation in the first millennium A.D.

The craft workers who are working on the Ardagh Chalice, they're taking, you know, interlays from the Mediterranean world, and they're imitating that in their own style.

Like, it's almost an Irish interpretation of other motifs that they're gathering from around Europe.

And that's what makes this period, the 8th century in particular in Ireland, So significant, is that you see this mix of art styles on a single object.

Also then, on the very famous Tara Brooch, which is just over 8cm in diameter.

And again, they've crammed every single motif and material onto this tiny object that they can possibly do.

So it is the finest piece of Irish jewellery from the first millennium A.D.

But there is no doubt that the wealth of the church and the importance of the church caused a lot of these objects to be created.

COLIN: This wealth would soon attract the attention of violent sea raiders from the north.

The monastery founded by St Aidan was one of the first to be attacked.

Vikings are arrived at Lindisfarne in the year 793 and the attack really sent shock waves through Europe at the time.

The contemporary scholar called Alcuin talks vividly of the blood of God's priests being splattered across the altar at Lindisfarne.

NARRATION: "Bitter and wild is the wind tonight, tossing the tresses of the sea to white.

On such a night as this I feel at ease.

Fierce Northmen only course the quiet seas."

COLIN: The fear implicit in the monk's lines was well placed.

The rich and famous monasteries were an easy target for Viking sea raiders.

CLARE: Iona saw a devastating series of attacks.

It was attacked by Vikings in 795.

They returned again in 802.

They came again in 806 when 68 members of the monastic community were slaughtered.

And they returned again in the year 825.

So as a result of the series of Viking attacks on Iona, they were granted land at another site at Kells in County Meath in the second decade of the 9th century, where a new community was set up as a place of retreat for the monks who were on Iona.

And it's thought that as a result of that the famous Book of Kells, which scholars think was created at the Church of Iona, moved across to Ireland, and that's why it's called the Book of Kells today.

COLIN: Monasteries in Ireland, especially those near the coast, were also subject to relentless attack.

Contemporary accounts for the year 825 tell of raid after raid by what they called heathens.

NARRATION: "Heathens invaded Bangor the great, Down was plundered by the heathens."

"Movilla with its oratories was burned by the heathens."

"The plundering of Inis Daimle by the heathens."

COLIN: Even the most remote of all Irish monasteries, the rocky fastness of Skellig Michael didn't escape.

Contemporary accounts tell the fate of the abbot Étgal.

NARRATION: "Étgal was carried off and died shortly afterwards of hunger and thirst."

By the middle of 837 the nature of the Viking raids had changed.

The raids grew even more ambitious and the attackers no longer confined themselves to coastal locations.

CLARE: They're raiding further inland.

They're using the river ways of the Boyne and the Shannon to travel to other Irish religious sites.

And by the end of the 830s, we start getting references to Viking camps being established in Ireland.

And this leads to the coining of a new word, longphort, which basically means a ship camp.

COLIN: These camps would become permanent settlements and Ireland's first cities: Limerick, Cork, Waterford and Wexford.

The largest and most important was Dublin.

LINZI: The sheer volume of Viking warriors that are actually flooding in and can't be underestimated.

They were all very young, between 17 and 20.

So this, you know, life was very short in Viking world.

From almost the very beginning, the Viking warriors were intermingling and intermarrying with the Irish population.

So you're straight away you're getting a mix of cultures.

COLIN: Viking Dublin grew to be a thriving city.

Exotic items such as amber and jet were being imported from all over the Viking world.

Trade also went the other way, with Dublin-made goods being traded across the North Atlantic.

This booming economy, however, had a very dark side.

Dublin had become one of the largest slave markets in Europe.

LINZI: Dublin was a very important international slave-trading station.

We have references to, you know, 780 people being taken in Armagh.

Of course, they would have taken the most able, probably from about the age of seven up, and they would have left the infants and the elderly people.

They were also importing slaves.

Slaves had been brought into Dublin, where they were being literally sold, probably at auction, and then shipped out around the Viking world.

And so it was a very vibrant place, but it was founded on on a lot of misery.

COLIN: By the year 1000, Dublin had become engaged, increasingly Christian and also increasingly wealthy.

Its king was Sitric Silkenbeard.

His major enemy was Brian Boru, King of Munster and High King of Ireland.

Brian Boru is a very important king in Irish history.

He's the only mediaeval king that managed to unite all of Ireland under his rule.

As such, he becomes this iconic figure in Irish history.

Brian's success was largely built on being able to take control of the Viking towns of Ireland, because these were great resources of wealth and manpower and fleets.

So he's able to take control of Limerick, Waterford.

But the reluctance of Dublin to be under the leadership of Brian Boru is what gives rise to the very famous Battle of Clontarf, which was fought on Good Friday in the year 1014.

COLIN: Contrary to popular belief that this was a battle between the native Irish and the Vikings, the Battle of Clontarf was a battle of alliances.

On both sides of the Battle of Clontarf, there were Irish and Vikings fighting side by side.

So Brian Boru's forces included troops from the Viking town of Limerick.

And the forces of Dublin that were fighting against Brian Boru included their allies from Leinster, who also didn't want to be under the power of Brian Boru.

Clontarf was also significant because it brought in combatants from outside Ireland as well.

So we, we hear of a leader from Alba, modern day Scotland, fighting on the side of Brian Boru.

But we also hear of Vikings from the Orkney Islands and the Hebrides fighting on the Dublin side.

COLIN: The battle raged from sunrise to sunset on that bloody day, on land and by sea.

EDEL: You do have fleets and they were fighting from ship to ship.

You would have had a lot of stabbing and a lot of blood and beheading, clearly, because Brian's son is beheaded and Cinnéide, who is his nephew, is beheaded.

It's very bloody.

COLIN: Brian's forces prevailed.

It was to be a bittersweet victory.

He was killed shortly after the battle by a Viking warrior.

Brian had been at prayer in his tent at the time.

NARRATION: "Brodir ran out of the woods and cut his way through the shield wall and swung at the king.

The blow cut off the king's head.

Then Brodir called loudly, let word go from man to man.

Brodir killed Brian."

Its significance has been talked up in later centuries to make it this epic narrative of good versus evil, Christianity versus paganism, Irish versus foreign oppressors.

COLIN: For centuries afterwards, the Battle of Clontarf would be portrayed as a significant victory for the Irish and Brian would be seen as a martyr who gave his life for his country and his faith.

Clontarf was far too important to be left simply to the hands of historians and it instead it passed into the hands of makers of legends.