Irish clans

Irish clans are traditional kinship groups sharing a common surname and heritage and existing in a lineage-based society, originating prior to the 17th century.^[1] A clan (or fine in Irish, plural finte) included the chief and his patrilineal relatives;^[2] however, Irish clans also included unrelated clients of the chief.^[3] These unrelated clients and their agnatic descendants were ineligible to be elected chief, but nonetheless assumed the name of the leading lineage as a show of allegiance.^[4]

Beginning in the 8th century, various genealogical collections were compiled purporting to trace the ancestry of these clans. Among them are genealogies in Rawlinson B 502, the Book of Ballymote, the Book of Lecan, the Leabhar Mór na nGenealach compiled by Dubhaltach MacFhirbisigh, and the Ó Cléirigh Book of Genealogies. In all of these cases, the genealogies listed state the agnatic descent of the chiefs and chieftains, and not necessarily every member of the clan. At least one genetic study has concluded that while these genealogies appear fairly accurate back to the Middle Ages, they are unreliable prior to the 7th century.^[5][6]