The O’Caseys (O Cathasaigh) were
originally lords of Saithne, in the north of the present County Dublin, until they were
dispossessed by the Normans under Sir Hugh de Lacy soon after the Anglo-Norman invasion
(twelfth cenwry). Afterwards they became an important Erenagh (church) family, being
hereditary keepers of Kilarduff and Dunfeeny in County Mayo, Cloondara and Tisrara in
County Roscommon, and Devinish in County Fermanagh.
The Ciarraighe Locha na nAirne
The Ciarraighe Locha na nAirne were originally part of a greater kingdom,
the tribal kingdom of Ciarraighe, centered at Cruachu (the ancient capital of Connacht).
This kingdom was fragmented by the Ui Briuin of the North Gaels during the late eighth
century or early ninth century. They may have been, in more ancient times, closely related
to the ancestors of the Oirghialla, the allies of the North Gaels (in the Heroic Age tales
of the North, the "Ulster Cycle," Cruachu is the center of the Gaelic-Laiginian
alliance). The Ciarraighe were indigenous to Connacht. Their main representatives in the
Middle Ages were the O’Kierans (O Ceirin) of northwest County Mayo. The native
territory of the O’Kierans was in the south of the barony of Costello, but they were
reduced in power there by the Anglo-Norman encroachment, and branches in Donegal and Clare
became more important.
The Ciarraighe Luachra
The Ciarraighe Luachra were the original tribe of North Kerry, a branch of
the Ciarraighe. Before the Anglo-Norman invasion had had a semiindependent kingdom between
Tralee and the Shannon. Their chief family was that of O’Connor (O Conchobhair) of
Kerry, whose stronghold was at Carrigafoyle, near Ballylongford. They held the Barony of
lraghticonor in the extreme north of County Kerry after the southern part of their
territory was encroached upon by the Fitzmaurices of Clanmaurice and other Norman
settlers. The O’Connors held lraghticonor down to the reign of Elizabeth, when it was
confiscated by the English and given to Trinity College.
The Eile were originally a tribe of western King’s County (Offaly),
where place-names recall their early residence in that region. After the battle of Druim
Derge (A.D. 516), at which battle they were decisively defeated by the expanding southern
Ui Neill, they migrated to the area known after them as "Ely" in the south of
Offaly and including northeast Tipperary. Their chief families in later times were the
O’Carrolls of Ely, the O’Mahers, the O’Riordans and the O’Flanagans.
The O’Carrolls (O Cearbhaill) descend
from Cearbhaill, Lord of Ely, who was one of the leaders at the famous battle of Clontarf
in 1014. The head of the O’Carrolls was originally lord of all Ely, but after the