The title of Earl of Desmond (Irish: Iarla Deasmumhan) has been held historically by lords in Ireland, first as a title outside of the peerage system and later as part of the Peerage of Ireland. The original Barony of Desmond in the province of Munster was held by descendants of Thomas FitzMaurice FitzGerald, Lord of O'Connelloe. Thomas was a younger son of Maurice FitzGerald, Lord of Lanstephan, a key supporter of Lord Pembroke ("Strongbow") in his 1169 invasion of Ireland. Maurice was the founder of the Cambro-Norman FitzGerald dynasty in Ireland. Being descended from a younger son of Maurice FitzGerald, the House of Desmond was a cadet branch of the Irish Geraldines; the senior branch, the House of Kildare, ancestors of the Dukes of Leinster, was founded by Thomas's elder brother, Geral