Again starting with an unusual Y-chromosome, they noticed its occurrence in a related set of surnames that were linked to branches of the Ui Neill, the clan that had held the High Kingship at Tara, and had expelled the Dal Riata to Argyll. The Ui Neill equivalent of Somerled was Niall Noigiallach, better known as Niall of the Nine Hostages, who lived in the second half of the fourth century AD. This was a time when the Romans were beginning to withdraw from mainland Britain. According to legend, Niall raided and harassed western Britain and specialized in capturing and then ransoming high-ranking hostages, hence his soubriquet. His most famous captive was one Succat, who went on to become St Patrick. Niall's military exploits carried him over the sea to Scotland, where he fought the Picts who were trying to retake the recent Irish colonies of Dalriada. It was during a raid even further afield, in France, that an arrow from the bow of an Irish rival killed Niall on the banks of the River Loire in AD 405. Niall was succeeded in the High Kingship by his nephew, Dathi, his father's brother's son. This was typical of the Gaelic tradition of derbhfine, the rules of inheritance that chose the new king from among the direct male relatives of the old. This served to ensure the patrilineal inheritance of the High Kingship itself