kingdom · British Isles

Deisi Muman

450 CE – 1200 CE (approx.)

Kingdom of the Déisi in Waterford and south Tipperary, whose legendary migrations reached Wales and whose name survives in the Decies.

Origins

The Déisi were a population group whose name means 'vassals'. The early Irish tale The Expulsion of the Déisi tells how they were driven from Brega near Tara and wandered south, some settling in Munster and others crossing to Dyfed in Wales, where the Kingdom of Dyfed's kings later claimed Déisi descent. In Munster they settled in what is now County Waterford and south Tipperary.

Rule and society

The Déisi Muman were a subject kingdom within the Kingdom of Munster, paying tribute to the Eóganachta of Cashel. The monastery of Lismore, founded by St Mochuda in the 7th century, was one of the great schools of early Ireland and lay in their territory. A northern branch, the Déis Tuaiscirt, later grew into the Dál Cais, the dynasty of Brian Bóruma.

Decline and legacy

The Ua Fáeláin, O'Phelan, kings ruled the Déisi in the 11th and 12th centuries. After the Anglo-Normans took Waterford in 1170 their lands were granted to settlers, and the kingdom faded around 1200. The name survives in the baronies of Decies in Waterford.

Connections (1)

More states of British Isles →

Cite this page
APA
The Epoch Institute. (2026). Deisi Muman. In The Epoch Institute States Register. https://the-epoch-institute.org/state/deisi-muman
MLA
“Deisi Muman.” The Epoch Institute States Register, The Epoch Institute, 2026, https://the-epoch-institute.org/state/deisi-muman. Accessed .
Chicago
The Epoch Institute. “Deisi Muman.” The Epoch Institute States Register. 2026. https://the-epoch-institute.org/state/deisi-muman.
Harvard
The Epoch Institute (2026) ‘Deisi Muman’, The Epoch Institute States Register. Available at: https://the-epoch-institute.org/state/deisi-muman (Accessed: ).

Last reviewed October 2026Random state ↻