Uí Bairrche was an Irish kin-based group that originally held lands in the south of the ancient province of Leinster

Leinster

Leinster is one of the Provinces of Ireland situated in the east of Ireland. It comprises the ancient Kingdoms of Mide, Osraige and Leinster. Following the Norman invasion of Ireland, the historic fifths of Leinster and Mide gradually merged, mainly due to the impact of the Pale, which straddled...

 (or Cóiced Laigen "the Fifth of the Laigin"). Another south Leinster kin group associated with the Uí Bairrche were groups of the Fothairt. The south of Leinster was dominated by the Uí Chennselaig in the 8th century. Uí Bairrche held lands around Carlow

Carlow

Carlow is the county town of County Carlow in Ireland. It is situated in the south-east of Ireland, 84 km from Dublin. County Carlow is the second smallest county in Ireland by area, however Carlow Town is the 14th largest urban area in Ireland by population according to the 2006 census. The...

, however Uí Chennselaig expansion split the kindred. The result was that one Uí Bairrche branch persevered in the Barrow valley; and another was forced to move south towards the Wexford

Wexford

Wexford is the county town of County Wexford, Ireland. It is situated near the southeastern corner of Ireland, close to Rosslare Europort. The town is connected to Dublin via the M11/N11 National Primary Route, and the national rail network...

 coast.

Following the medieval genealogies, the Uí Bairrche descend from Dáire Barrach, a son of Cathair Mór

Cathair Mor

Cathair Mór , son of Fedlimid Fir Urglais, a descendant of Mug Corb, was, according to medieval Irish legend and historical tradition, a High King of Ireland. He took power after the death of Fedlimid Rechtmar. He is said to have had thirty sons, but only ten of them had children; several medieval...

, and are thus of Laigin

Laigin

The Laigin, modern spelling Laighin , were a population group of early Ireland who gave their name to the province of Leinster...

 origins. T. F. O'Rahilly

T. F. O'Rahilly

Thomas Francis O'Rahilly was an Irish scholar of the Celtic languages, particularly in the fields of Historical linguistics and Irish dialects. He was a member of the Royal Irish Academy.-Biography:He was born in Listowel, County Kerry, Ireland...

, however, believed them to have originally belonged to the Érainn, being descendants of an ancestor figure Dáire (*Dārios).

Genealogies for the Uí Baircche are recorded in Rawlinson B 502, fos. 121-2. Among the monasteries in Leinster controlled by the Uí Bairrche are Cell Auxili, Slébte (Sletty), Glenn Uissen (now Killeshin), Banba Mór, Cell Mo Lappóc and Tech Mo Shacro.