UÍ BRIÚINMacShamhráin, Ailbhe. “The Emergence of the Metropolitan
See: Dublin 1111–1216.” In History of the Catholic Diocese
of Dublin, edited by J. Kelly and D. Keogh, pp. 58–62.
Dublin: Four Courts Press, 2000.
Martin, F. X. “St. Bernard, St. Malachy, St. Laurence O’Toole.”
Seanchas Ardmhacha15, no. 1 (1992): 19, 25, 28, 30–32.
See alsoChurch Reform, Twelfth Century;
Hagiography
UÍ BRIÚIN
Origins
From the late eighth century until the Anglo-Norman
invasion, the Uí Briúin were the most powerful dynasty
in Connacht. Their eponym—Brión son of Eochu
Mugmedón, king of Ireland, by Mongfhind, daughter
of the Munster king Feradach son of Dáre Cerbba—
is depicted by the genealogies and saga literature as
the elder brother of Fiachrach and Ailill, ancestors of
the early Connacht dynasties of Uí Fiachrach and Uí
Ailella. Their half-brother, the son of Eochu by the
British slave girl Cairenn Casdub, was said to be Niall
Noígiallach (“of the Nine Hostages”), ancestor of the
Uí Néill. It is uncertain whether the depiction of the
eponyms as brothers reflects actual bonds of kinship
or was simply a biological metaphor for political rela-
tionships between the dynasties concerned.
Dynasts alleged by the genealogists to have been
members of the Uí Briúin appear in the annals by the
early sixth century. The earliest references to Uí Briúin
specifically as a dynasty, however, are mid-seventh
century, occurring both within a series of annal entries
and in Tírechán’s life of Patrick. Tírechán relates that
the saint traveled to Duma Selchae in Mag nAí, where
the “halls of the sons of Brión” were located. Tírechán
neither enumerates nor names these sons, but the
equivalent passage in the Vita Tripartita, a possibly
ninth-century life of Patrick, names six sons of Brión.
A series of later sources dating from the eleventh cen-
tury onward, meanwhile, enumerates Brión’s progeny
as no less than twenty-four. No doubt the increasing
power of the Uí Briúin was responsible for this dramatic
swelling of the ranks, as tribes and dynasties newly
coming under Uí Briúin sway were furnished with
ancestries that would link them genealogically to their
overlords. Into this category fall the Uí Briúin Umaill
and likely also the Uí Briúin Ratha and Uí Briúin Sinna.
Uí Briúin Aí
According to the later sources, Brión’s youngest son,
Duí Galach, was the ancestor of the three most impor-
tant branches of the dynasty: Uí Briúin Aí, Uí Briúin
Bréifne, and Uí Briúin Seóla. Of the three, by far the most
powerful branch of the dynasty was Uí Briúin Aí, based
in Mag nAí in north-central County Roscommon.
Throughout the seventh and first half of the eighth cen-
turies, Uí Briúin Aí struggled with Uí Fiachrach to con-
trol the kingship of Connacht. By the end of the eighth
century, they had managed to squeeze out their Uí
Fiachrach rivals to gain a near monopoly on the provin-
cial kingship. At this point, the controlling branch of the
Uí Briúin was a sept known as Síl Muiredaig whose
ruling family were to become the Ua Conchobair
dynasty. Spreading out from their Mag nAí homeland,
Síl Muiredaig took direct control over most of modern
County Roscommon and much of east Galway, in addi-
tion to their overlordship of the rest of the province.
From the late eighth century until the coming of the
Anglo-Normans, Uí Briúin Aí provided all but six kings
of Connacht. They lost their grasp on the kingship once
in the mid-tenth century as a consequence of intense
rivalry from within Síl Muiredaig, and five times in the
eleventh century when they faced fierce opposition from
Uí Briúin Bréifne and Uí Briúin Seóla within Connacht,
and from the Uí Briain of Munster without. After the
vicissitudes of the eleventh century, however, the Uí
Briúin Aí made a remarkable recovery in the twelfth,
not only firmly recovering the kingship of Connacht but
also gaining the kingship of Ireland in the personages
of Tairrdelbach Ua Conchobair and his son Ruaidrí.Uí Briúin Bréifne
On those occasions when Uí Briúin Aí lost control of
the Connacht kingship, it was predominantly dynasts
from Uí Briúin Bréifne, specifically the ruling family of
Ua Ruairc, who seized the kingship. Having crossed east
of the Shannon by the late eighth century into present
day counties Leitrim and Cavan, Uí Briúin Bréifne grad-
ually expanded in a diagonal direction so that at the peak
of their power in the late twelfth century they controlled
a diagonal band of territory stretching from Leitrim and
northeast Sligo down to Kells and Drogheda. Although
under the suzerainty of the king of Connacht, most of
this kingdom lay beyond the technical limits of the prov-
ince, defined as west of the Shannon.Uí Briúin Seóla
Least powerful of the three main Uí Briúin dynasties,
but by no means inconsequential, were Uí Briúin Seóla.
Also known as the kings of “Uí Briúin In Déisceirt”
(“Uí Briúin of the south”) and of “Iar-Chonnacht”
(“west Connacht”), the Uí Briúin Seóla were based in
the area around Moyola, County Galway, east of Lough
Corrib. Their two main divisions were the Clann