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King of Airgialla

Oriel
Airgíalla
331–1585
Oriel before the Norman invasion of Ireland
Capital Not specified
Languages Middle Irish, Early Modern Irish, Latin
Religion Gaelic Christianity
Catholic Christianity
Gaelic tradition
Government Tanistry
 •  331–? Colla Uais
 •  1579–1585 Rossa Buidhe Mac Mathghamhna
History
 •  Established 331
 •  Disestablished 1585
Preceded by
Succeeded by
Ulaid
Kingdom of Ireland

Airgíalla (Modern Irish: Oirialla, English: Oriel) was a medieval Irish over-kingdom and the collective name for the confederation of tribes that formed it. The confederation consisted of nine minor-kingdoms, all independent of each other but paying nominal suzerainty to an overking, usually from the most powerful dynasty. Airgíalla at its peak roughly matched the modern dioceses of Armagh and Clogher, spanning parts of counties Armagh, Monaghan, Louth, Fermanagh, Tyrone and Londonderry. Its main towns were Armagh and Clogher.

According to legend, Airgíalla was founded by the Three Collas, who are said to have conquered what is now central Ulster from the Ulaid. The decisive victory was the battle of Achadh Leithdheirg, said to have been fought around the year 331. However, this tale is thought to be mostly fiction, and the actual year and circumstances of how the Airgíalla confederation came about is unknown.

Originally thought to have been under the dominance of the neighbouring Ulaid to the east, the territory of the Airgíalla from the 6th century onwards was gradually eroded by the encroachment of their northern neighbours, the Cenél nEógain of the Northern Uí Néill, as well as the Southern Uí Néill to their south. From 735 they fell under the dominance of the Cenél nEógain, and by 827 had become their vassals. The kingdom of Airgíalla was at its peak in the 12th century, under king Donnchad Ua Cerbaill. The later constricted kingdom of Airgíalla survived in Monaghan—which was known as Oirghialla and Oriel after the Norman Invasion of Ireland—under the Mac Mathghamhna, until the end of the Gaelic order in Ireland.


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