Development and History
Before the destruction of the Gaelic order in the seventeenth century the O Mulvenna sept was located in O'Cahan's country in Co. Derry where they were hereditary 'ollavs' to the O'Cahans (O'Kane); ollavs were a learned class who acted as hereditary custodians of the national memory and of oral literature and whose knowledge of pedigree and history enabled them, in return for handsome gifts, to feed the pride of the Gaelic aristocracy. Until 1603, they were the main support and champions of the Old Gaelic Order. The earliest reference to the name occurs in the Annals of Ulster in 1164 in which the first O Mavil Mheana figures. The name appears as O Mulvenna in the 1659 'census' while more modern birth statistics indicate that Mulvany is the usual form of the name outside northern Ulster. MacIlvenny belongs to north east Ulster but is not numerous.