Complex sentence: Richard Mór de Burgh, 1st Baron of Connaught (c.1194--1242), Justiciar of Ireland was the eldest son of William de Burgh and a daughter of Domnall Mór Ua Briain, King of Thomond.
Split into simpler sentences: Richard Mór de Burgh, 1st Baron of Connaught (c.1194--1242), Justiciar of Ireland. De Burgh was the eldest son of William de Burgh and a daughter of Domnall Mór Ua Briain, King of Thomond.