Mr N Thuathail was a Queenconsort of Leinster as the principal first wife of King Diarmait Mac Murchada. Under Brehon Law, Irish men were allowed more than one wife. King Dermots second wife was Sadhbh N Fhaolain.
Mr was born in Castledermot, Kildare, Ireland in about 1114, the daughter of Muirchertach Ua Tuathail, King of the U Muirdeaigh, and Cacht N Morda.
Source: Wikipedia