You share a paternal-line ancestor with Niall of the Nine Hostages.
The spread of haplogroup R-M269 in northern Ireland and Scotland was likely aided by men like Niall of the Nine Hostages. Perhaps more myth than man, Niall of the Nine Hostages is said to have been a King of Tara in northwestern Ireland in the late 4th century C.E. His name comes from a tale of nine hostages that he held from the regions he ruled over. Though the legendary stories of his life may have been invented hundreds of years after he died, genetic evidence suggests that the Uí Néill dynasty, whose name means "descendants of Niall," did in fact trace back to just one man who bore a branch of haplogroup R-M269.
The Uí Néill ruled to various degrees as kings of Ireland from the 7th to the 11th century C.E. In the highly patriarchal society of medieval Ireland, their status allowed them to have outsized numbers of children and spread their paternal lineage each generation. In fact, researchers have estimated that between 2 and 3 million men with roots in north-west Ireland are paternal-line descendants.
|Niall of the Nine Hostages apparently burning one of them,|
or at least someone not likely to reproduce much more.
I'm still trying to figure out how Irish conquerors picked the area of Breconshire. It's not exactly conveniently located with regard to Ireland or anywhere else for that matter.