Kingdom of Munster

Kingdom of Munster Mumhain
1st century BC–1118
The Mac Cárthaigh as leaders of the Eóganacht Chaisil provided many kings of Munster from the 7th century onwards and established Cork.
A map of Munster in the 10th century, with boundaries accounting for the loss of Osraige.
Capital	Cork
Common languages	Primitive Irish, Old Irish, Middle Irish, Latin
Religion	Gaelic Christianity Catholic Christianity Gaelic tradition
Government	Tanistry
Rí
• 1st century BCE	Deda mac Sin
• 1118	Muirchertach Ó Briain
History
• Established	1st century BC
• Disestablished	1118
ISO 3166 code	IE
Succeeded by Kingdom of Osraige Kingdom of Desmond Kingdom of Thomond
Today part of	Ireland

The Kingdom of Munster (Irish: Ríocht Mhumhain) was a kingdom of Gaelic Ireland which existed in the south-west of the island from at least the 1st century BC until 1118. According to traditional Irish history found in the Annals of the Four Masters, the kingdom originated as the territory of the Clanna Dedad (sometimes known as the Dáirine), an Érainn tribe of Irish Gaels. Some of the early kings were prominent in the Red Branch Cycle such as Cú Roí and Conaire Mór. For a few centuries they were competitors for the High Kingship of Ireland, but ultimately lost out to the Connachta, descendants of Conn Cétchathach. The kingdom had different borders and internal divisions at different times during its history.

Major changes reshaped Munster in the 6th century, as the Corcu Loígde (ancestors of the Ó hEidirsceoil) fell from power. Osraige which had been brought under the control of Munster for two centuries was retaken by the Dál Birn (ancestors of the Mac Giolla Phádraig). Various subordinate groups, such as the Múscraige, switched their alliance and helped to bring the Eóganachta to power in Munster. For the next three centuries, various subgroups such as the Eóganacht Chaisil (ancestors of the Ó Súilleabháin and Mac Cárthaigh)^[1] and Eóganacht Glendamnach (ancestors of the Ó Caoimh) competed for control of Munster. Celtic Christian civilisation developed at this time and the Rock of Cashel became a seat of power. Two kings, Faílbe Flann mac Áedo Duib and Cathal mac Finguine, were able to raise Munster to the premier Irish kingdom for a time.

Munster had to contend with raids from the Vikings under the Uí Ímair from the 9th century onwards, who established themselves at Limerick, Waterford and Cork. Around the same time the Dál gCais (ancestors of the Ó Briain),^[2] previously known as the Déisi, were also in the ascendancy in Munster. Aided in part by the Uí Néill, the previously subordinate Dál gCais came to challenge the Eóganachta for control of Munster. The exploits of their most famous member Brian Bóruma, who is known for the Battle of Clontarf established Dál gCais rule for the rest of the 11th century. After internal divisions, Munster was partitioned by High King Toirdelbach Ó Conchobhair with the Treaty of Glanmire in 1118, between Thomond ruled by the Ó Briain and Desmond ruled by the Mac Cárthaigh.