This family is descended from Jordan De Courcy, who was a younger brother of Sir John De Courcy, the first Earl of Ulster, from him they derive the surname MacJordan, now Jordan in English and MacSuirtáin in Irish. When, however, the first of the family came to Ireland with the Anglo-Norman invaders, around 1170 they were known by the name De Exeter. Like many of the Norman families, especially their Mayo neighbours the Burkes, they became "as Irish as the Irish themselves," adopting Irish customs and Brehon laws and forming a sept in the traditional Gaelic manner. Hence the abandonment of their Norman name and assumption of the patronymic MacJordan. In The Antiquities of Ireland, by Sir James Ware we find that: "The De Exonias or De Exeters submitted to be called MacJordans, from one Jordan De Exonia, who was the first founder of the family."