Munster (Irish: an Mhumhain / Cúige Mumhan, pronounced , ) is one of the provinces of Ireland situated in the south of Ireland. In early Ireland, it was one of the "fifths" ruled by a "king of over-kings" Irish: rí ruirech. Following the Norman invasion of Ireland, the ancient kingdoms were shired into counties for administrative and judicial purposes. In later centuries, local government legislation has seen further sub-division of the historic counties.
Munster has no official function for local government purposes. For the purposes of the ISO, the province is listed as one of the provincial sub-divisions of the State (ISO 3166-2:IE) and coded as "IE-M". Geographically, Munster covers a total area of 24,675 km2 (9,527 sq mi) and has a population of 1,280,020, with the most populated city being Cork. Other significant urban centres in the province include Limerick and Waterford.
In the early centuries AD, Munster was the domain of the Iverni peoples and the Clanna Dedad familial line, led by Cú Roí and to whom the king Conaire Mór also belonged. In the 5th century, Saint Patrick spent several years in the area and founded Christian churches and ordained priests. During the Early Middle Ages, most of the area was part of the Kingdom of Munster, ruled by the Eóganachta dynasty. Prior to this, the area was ruled by the Dáirine and Corcu Loígde overlords from the early 7th century onwards, perhaps beginning with the career of Faílbe Flann mac Áedo Duib. Later rulers from the Eóganachta who would dominate a greater part of Ireland were Cathal mac Finguine and Feidlimid mac Cremthanin. Notable regional kingdoms and lordships of Early Medieval Munster were Iarmuman (West Munster), Osraige (Ossory), Uí Liatháin, Uí Fidgenti, Éile, Múscraige, Ciarraige Luachra, Corcu Duibne, Corcu Baiscinn, and Déisi Muman. By the 9th century, the Gaels had been joined by Norse Vikings who founded towns such as Cork, Waterford and Limerick, for the most part incorporated into a maritime empire by the Dynasty of Ivar, who periodically would threaten Munster with conquest in the next century. Around this period Ossory broke away from Munster. The 10th century saw the rise of the Dalcassian clan, who had earlier annexed Thomond, north of the River Shannon to Munster. Their leaders were the ancestors of the O'Brien dynasty and spawned Brian Boru, perhaps the most noted High King of Ireland, and several of whose descendants were also High Kings.
By 1118, Munster had fractured into the Kingdom of Thomond under the O'Briens, the Kingdom of Desmond under the MacCarthy dynasty (Eóganachta), and the short-lived Kingdom of Ormond under the O'Kennedys (another Dalcassian sept). The three crowns of the flag of Munster represent these three late kingdoms.
There was Norman influence from the 14th century, including by the FitzGerald, de Clare and Butler houses, two of whom carved out earldoms within the Lordship of Ireland, the Earls of Desmond eventually becoming independent potentates, while the Earls of Ormond remained closer to England. The O'Brien of Thomond and MacCarthy of Desmond surrendered and regranted sovereignty to the Tudors in 1543 and 1565, joining the Kingdom of Ireland. The impactful Desmond Rebellions, led by the FitzGeralds, soon followed.