The Ui Ceinnsealaigh
The Ui Ceinnsealaigh were the most powerful
tribe of Leinster, and usually held the provincial overkingship until the time of the
AngIo-Norman invasion (which their representative, King Dermot MacMurrough of Leinster,
helped bring about). The center of their power lay around the Diocese of Ferns, in
northern Wexford. Their chief families were the Kavanaghs, Kinsells, O’Murphys and
The Kavanaghs (Caomhanach) descend from Domhnall (Donal) Caomhanach,
son of Diarmaid Mac Murchadha (Dermot MacMurrougb), King of Leinster at the time of the
Anglo-Norman invasion (died 1171). He was called "Caomhanach" as a result of his
having been fostered by the Co-arb (blood-related successor) of St. Caomhan at Kilcavan
near Corey. The adoption by his descendants of Kavanagh (i.e., "belonging to St.
Caomhan") as a family name is unusual: It is, like Kinsella below, one of the very
few non-patronymic names used among the pre-Norman Gaelic population. The patrimony of the
family included extensive districts in counties Carlow and Wexford, where the name is very
The Kinsellas (Cinnsealach,) descend from Enna Cinnsealach, brother of
Domhnall Caomhanach (Kavanagh) and son of Dermot MacMurrogh. They possessed most of the
barony of Gorey in the north of County Wexford, where they remain to this day, but they
remained much less numerous than their kinsmen, the Kavanaghs. Their lands were formerly
referred to as "the Kinsellaghs." A branch of the Kinsellas, the O’Murphys
(O Murchadha) of Muskerry, settled early in County Cork, where they became connected with
the barony of Muskerry in the west-central part of that county.
The O’Morchoes, or O’Murphys (O Murchadha) were chiefs of Ui
Feilme, now the Barony of Ballaghkeen in the northeast of County Wexford, all along the
coast. They maintained their independence and identity as a clan down to the first part of
the seventeenth century, and are now very numerous throughout Leinster.
The Ui Dunlainge
The Ui Dunlainge anciently inhabited the
Liffey Plain, the territory around the River Liffey, just to the northwest of the Wicklow
Mountains. They were very important in north Leinster, and held the provincial
overkingship of Leinster itself from 738 to 1042, alternating it between their chief
clans, the Ui Dunchada, Ui Faelain and Ui Muiredaig. Their representatives in later times
were the O’Byrnes and O’Tooles.
The Ui Faelain included the O’Byrnes (O Broin) and their kinsmen the MacKeoghs or
Kehoes (Mac Eochaidh) of Leinster. The O’Byrnes descend from Bran, son of Maolmordha,
King of Leinster in 1014. Maolmordha died fighting on the side of Earl Sigurd of Orkney
against Brian Boru, High-King of Ireland, at the battle of Clontarf in 1014).