Cenél Conaill: The race name of the O'Gallagers, O'Boyles and other families traditionally descended from Conall Gulban, son of Niall of the Nine Hostages, located in Tirconnell.

Cenél Eoghain: The clan name of the O'Neills etc. descended from Eoghan, son of the Nine Hostages, located in Tyrone and south Derry.

Dál gCais: Otherwise called the Dalcassians; embraces the main septs/clans of Thomond.

Eoghanacht: The clan name of the descendants of Eoghan, son of Oilioll Olum, to which many of the main families of south Munster belonged.

Síol Anmchadha: A branch of the Uí Maine.

Sí Muireadhaigh (Silmurray) The clan of the O'Connors and other north Connacht septs.

Uí Fiachrach: The northern and more important, ie. Uí Fiachrach Muaidhe, were located in north Mayo and Slico; the other branch (Aidhne) occupied that part of south Galway covered by the small diocese of Kilmacduagh.

Uí Maine (At one time anglicized Hy Many): Mid-Galway and south RoscommonP>Desmond (Deasmhumhan): Kerry and much of Co. Cork.

Iar Connacht: West Connacht, mainly Connemara.

Muskerry (Muscraidhe) North-west and central Cork.

Oriel (Orghialla): Cos. Armagh and Monaghan and parts of south Down, Louth and Fermanagh.

Ormond (Urmhumhan): Much of Co. Kilkenny and north Tipperary.

Ossory: The extent of the ancient kingdom of Osraighe was apporoximately the same as that of the diocese of Ossory, ie. Co. Kilkenny and some adjacent areas.

Thomond (Tuathmhumhan): Most of Co. Clare with adjacent parts of Cos. Limerick and Tipperary.

Tirconnell (Tir Chonaill): Co. Donegal.

Tirowen (Tir Eoghain): Co. Tyrone with adjacent part of Co. Derry.