The latter cantred, variously called Muscry-donnegan or "O'Donegan's country" or "Múscraighe Tri Maighe", was a rural deanery in the Diocese of Cloyne.
[3][4] These cantreds or baronies had been expropriated by another (half) first cousin, Ralph Fitz-Stephen (died 1182), the grandson of Nesta by Stephen, Constable of Cardigan.
[6] In 1267, King Henry III of England appointed Lord David de Barry as Chief Justice of Ireland.
The most prominent Gaelic neighbours of the de Barrys were the MacCarthy Reagh dynasty, rulers of the principality or petty kingdom of Carbery.
They were made to descend from Fothach Canann,[13] fifth son of the famous Lugaid Mac Con of the Dáirine or Corcu Loígde.
The Uí Liatháin or "Sons of Liathán", whose long-decayed and defunct kingdom the de Barrys by coincidence came to occupy, are notable for having raided other parts of Britain in antiquity from their fortresses in Wales and Cornwall.
Also, notable is that the de Barry family descend maternally, through Angharad and Nesta, from the ancient Welsh prince Cunedda, whose sons were the Britons who ended the Uí Liatháin's dominance in Wales.