Kildare: (Munster) In the reign of King John, parts of the territories of Moy Liffey, Offaley, Leix, and Cualan, were formed into the county Kildare; but it was only a "liberty" dependent on the Jurisdiction of the Sheriffs of Dublin, until A.D. 1296, in the reign of Edward the First, when Kildare was constituted a distinct county. It was called Coill-dara, or the "Wood of Oaks," as oak forests abounded there in ancient times; or, according to others, Cill-dara or the "Church of the Oaks," as it is said that the first church founding.

Uí Dúnlainge  The rise of the Úí Dúnlainge in Leinster appears to coincide with that of the rise of the southern Úí Neill in Meath and Westmeath, indicating perhaps a defeat of former dominant tribes by the southern Úí Neill, or perhaps indicating an earlier Úí Dúnlainge connection in that area to the north. The Uí Dúnlainge dynasty branched out into the three powerful septs of Úí Muiredaig (e.g. O'Toole), Úí Dúnchada (e.g. Fitz Dermot), and Úí Fáeláin (e.g. O'Byrne). From the 6th to the 9th centuries, the Úí Dúnlainge monopolized the kingship of Leinster. With their principal stronghold at Naas, they also dominated northern Leinster (excluding Brega and Mide) from at least the 8th century to the time of the Norman Invasion.

Úí Dúnchada (e.g. Mac Gilla Mo-Cholmóg, FitzDermot) Dublin,
The traditional lands of the powerful Úí Dúnchada sept of the Úí Dúnlainge were on the borders of counties Kildare and Dublin (and perhaps Wicklow), between the river Liffey and the 'Dublin' mountains.Descendants of one of their early kings, Mac Gilla Mo-Cholmóg of the mid 11th century, are said to have taken on the surname Fitz Dermot. 

Uí Fergusa, Dublin
Descended Fergus son of Dúnlang, son of Enna Nia, son of Bressal Bélach, son of Fiachu Baicced, son of Cathir Mor.The Uí Fergusa were a sub-sept of the Uí Dúnlainge with their traditional territory immediately west of Dublin prior to the arrival of the Vikings. The Book of Leinster, Book of Ballymote, and other sources give their territory between the river Liffey and Fir Cualand (Cuallan). The genealogies of Rawlinson B502 mention Fergus m. Dúnlaing, a quo Úi Fergusa eter Liphi, again referring to their presence by the river Liffey.

Úí Muiredaig (e.g. O'Toole)The Úí Muireadhaigh, later represented by the Ua Tuathail (O'Tooles) are said to descend from Ughaire, a King of Leinster (died 956). They were Chiefs of what is now the southern half of County Kildare. This area has been cited, in Crede Mihi (written circa 1270, ed. Gilbert) as comprising the baronies of Kilkea and Moone, Narragh with Reban East and West, and parts of Connell, in co. Kildare, plus the plus west half of Úí Mail, in co. Wicklow. They were later driven from this territory following the Anglo-Norman invasion, afterwards retiring to the mountain fastness of the Wicklow mountains, like their Úí Faeláin kinsmen.

 

O'Bracain or O'Bracken

Chiefs of Moy Liffey. The O'Murcans and O'Brackens appear to have possessed the districts along the Liffey, near Dublin

O'Clardha or O'Carey

Chiefs of Cairbre O'Ciardha, now the Barony of "Carbery" in the county Kildare

O'Colgan , MacDonnell, O'Dempsey, and O'Dunn

Chiefs of note in Kildare

O'Cullin or O'Cullen

Chiefs of Coille Culluin (or the Woods of Cullen), now the Barony of "Kilcullen" in the county Kildare

O'Dubthaigh or O'Duffy

one of the Leinster clans of the race of the Monarch Cahir Mór; and of the same descent as MacMorough, kings of Leinster, and O'Toole and O'Byrne, Chiefs of Wicklow. Originally located in Kildare and Carlow, and afterwards in Dublin and Meath, the O'Duffys migrated in modern times to Louth, Monaghan, Cavan, Galway, and Roscommon. Dugan mentions macGiolla-mocholmog or Gilcolm, and O'Dunchada or O'Donoghoe, as Lords of Fingal, near Dublin: and, as mentioned in the chapter on "Hy-Kinsellagh," there was another MacGiollamocholmog, Lord of a territory on the borders of Wicklow

O'Fagan or MacFagan

considered by some to be of English descent. D'Alton, in his "History of the County Dublin," mentions some of this family who, in the thirteenth, fourteenth, and fifteenth centuries were high sheriffs, in Meath and Dublin. In former times the Fagans of Feltrim, near Dublin, and other parts of that county, were highly respectable, and held extensive possessions

O'Fiachra

Chiefs of Hy-Ineachruis at Almhuin [Allen]; and O'Haodha or O'Hea, Chiefs of Hy-Deadhaidh: territories comprised in the county Kildare

O'Gealbhroin

Chiefs of Clar Liffé, or the Plain of the Liffey, a territory on the borders of Dublin and Kildare

MacFogarty

Lords of South Bregia, are mentioned by the Four Masters in the tenth century

O'Murcain or O'Murcan

O'Muirthe or O'Murtha

Chiefs of Cenél Flaitheamhuin (or Clan Fleming); and O'Fintighearan, Chiefs of Hy-Mealla: territories also situated in the county Kildare, it would appear in the baronies of East and West Ophaley or Offaley

O'Murphy

Chiefs in Wexford, were also numerous in the counties of Dublin and Meath

O'Mullen

numerous in Meath, Dublin, and Kildare

O'Muircheartaigh, O'Moriarty, or O'Murtagh

Chiefs of the tribe of O'Maine; and O'Modarn, Chiefs of Cenél Eochain, are mentioned by O'Dugan as Chiefs of the Britons or Welsh; and appear to have been located near Dublin

MacMuireagain

Lords of East Liffey, in the tenthcentury