He was the fearless High King who battled the English, the Scots, the French, and the Romans. Taking hostages, striking fear into the hearts of his enemies and even kidnapping Saint Patrick to bring to Ireland as a slave. But historians often speculate that Niall of the Nine Hostages was just a legend and a mythical figure that never really existed. Here we describe the genetic analyses that confirmed the great genetic dynasty of this prehistoric Irish king and the existence of 3 million “descendants of Niall.”

The legend of Niall Niogiallach

Legends speak of Eochaid, a High King of Ireland, who ruled with his beautiful dark-haired queen Mongfind. Until one day the king fell in love with one of his hostages, a maiden named Cairenn. Of course, the queen grew to hate Cairenn.

When she found out that Cairenn was carrying the king’s child, Mongfind forced hard physical work upon her, hoping she would lose the baby. But Cairenn was strong and able. One day on her way to the well to fetch water, she gave birth to a son. Deathly afraid of Mongfind, Cairenn refused to even touch the baby. Instead, picked up her water bucket to return to the house.

The baby was discovered by a poet called Torna. When Torna touched the infant, he knew who the child was, and that he would grow up to be king. Such was the beginning of the life of Niall Noigiallach aka “Niall of the Nine Hostages” – hated by the queen, unwanted by his mother and accidentally discovered by a kind-hearted soul. This boy would grow up to be one of the greatest of Irish kings.

Descendants of Niall

Niall was the High King of Ireland in the fifth century. It’s said that he consolidated his power by leading raids on the Roman Empire. At each conquest, he took a hostage from the rival royal family to ensure his domain. The number of hostages amounted to nine, earning him the name Niall of the Nine Hostages. Saint Patrick was said to have been kidnapped and brought to Ireland as one of his hostages during his raids.

Niall was the founder of the dynasty Uí Néill “descendants of Niall,” one of the most powerful dynasties of ancient Ireland, ruling Ireland until the 11th century. Niall reportedly had 12 sons, many of whom became powerful kings, especially in the northwest.

In fact, all but two of the High Kings at Tara were descendants of Niall. According to tradition, Niall died outside of Ireland. Some sources indicating that he died at sea fighting Eorchaid mac Enna, the King of Leinster and others suggesting that he died fighting against the Picts in Scotland.

DNA proof of a legend

However, there have always been doubts that Niall actually existed, since his rule was prior to written records. Sources for Niall’s existence as a historical king come from Lebor Gabala Erenn, Annals of the Four Masters, which chronicles legendary tales such as the Adventure of the Sons of Eochaid Mugmedon, and The Death of Niall of the Nine Hostages.

Historians have often speculated that Niall was just a mythological figure, a mere legend, until researchers from Trinity College in Dublin put these claims to the test using DNA analyses.

DNA Paternal Ancestry Test box

DNA Paternal Ancestry Test

The researchers looked at Y-DNA STRs (short tandem repeats), regions of DNA that are repeated many times over, and are useful to trace paternal ancestry. Y-DNA is passed down from father to son, which means all males who have descended from the same paternal lineage will have the same Y-DNA profile.

They generated Y-STR profiles of 796 Irish men from all over Ireland, and found a specific unique Y-DNA STR marker profile in a large proportion of Irish men.

This profile was more frequent in the men that came from the northwestern part of the island, particularly the historical regions that were once under Uí Néill power. It was also associated strongly with surnames that were thought to descend from the Uí Néill lineage.

Are you a descendant of this great Irish King?

What does this mean? DNA evidence is in agreement with the ancient fables about Niall. It appears that he really did exist. Today, one in five males in Northern Ireland carries this unique Y-DNA STR profile and is likely a descendant of Niall.

Even outside of Ireland, 1 in 10 men in western and central Scotland also carry this profile, as well as 2% of European American New Yorkers, likely due to the historically high rates of Irish emigration to North America.

According to this study, Niall of the Nine Hostages may be the forefather of approximately three million men in the world today. If you have taken the DNA Paternal Ancestry Test, you can see if you have also descended from the Uí Néill lineage founded by the great Niall.


Moore T et al. (2006) A Y-Chromosome Signature of Hegemony in Gaelic Ireland. Am J Hum Genet. 78(2):334-338.

Maugh TH. (2006) An Irish King Rules Gene Pool. Los Angeles Times. 2006 Jan 21.

Kennedy S. (2006) Irish genes span the globe, and one king spawned nearly all. The Sydney Morning Herald. 2006 Jan 19.

Battles J. (2006) High King Niall: the most fertile man in Ireland. The Sunday Times (UK). 2006 Jan 15.</a