In Co Fermanagh, where the name Monaghan is numerous, the Fir Manach family are thought to be part of the original inhabitants of the area, the Fir Manach, from whom the county gets its name. Their base was in the district of Lurg. The Monaghan name migrated into Coleraine and the Goidelic kingdom of Dalriada: the adjoining counties of Monaghan and Derry.
As tradition has it the ancient Manaigh or Monaigh migrated from south Leinster (Ossory) to an occupied the area of Ely near Lough Erne, giving their name to the modern county of Fermanagh. County Kilkenny forms much of what was known as the kingdom of Ossory. Located in western Co. Cavan and northern Co. Meath, the Mugdorna occupied the territory of the Fir Roiss prior to 800 AD, when they were pushed out of Meath and into Monaghan and replaced by the Gailenga.
The Monaigh of Uladh migrated to the region of Downpatrick, which is located in the barony of Lecale (Leth Cathail), County Down and in Roscommon and Galway. The Book of Uí Maine places the Cenél Mailche in Monach.
The Monaig are often associated with the Manapioi (Menapii), a maritime Belgic tribe of Cassel, Northern Gaul who are noted on Ptolemy's 2nd century map of Ireland in southeast Ireland and Breton. They spread northwards as the Fir Manach, or Monaig in Irish. Early Irish genealogists claim they migrated from south Leinster (Ossory), their descent from the ancient Laiginian ancestor-god, Catháer Máir.
The barony of Dartree in west co. Monaghan, was also referred to as Dartaige Coininnsi. The O'Boylan, O' Beolain, (Ó Baoighealláin) sept are cited as early kings of Darty (Dairtre) in Orghialla.
The Uí Tuirtre of South Derry moved eastward across the River Bann as their lands were absorbed into the expanding Uí Neill over-kingdom of Cenél Eoghain in the eighth century. They kept their western lands (the present barony of Loughinsholin) as a tributary kingdom to the Cineal Eoghain, but resided in Lough Beg, which lay strategically between their new and old territories. East of the Bann they were allies of the Dal nAraidi.
The Clan Conchobhair, of the Cenél Éoghain, said to be originally of Magh Ithe and certain septs moving into county Derry about the 10th-11th century. The Ciannachta of Glenn Geimin were succeeded by the O'Cathains in the 12th century.
From the time of Malcolm III and his cousin Gospatrick of Dunbar, the patronymic O’Ceann-Mor, Skene, in his Highlanders of Scotland, ingeniously converts into O’Cathan, and so makes out that the race is a branch of the great Clan Chattan or Siol O’Cain of Cromarty as son-of-the-chief.. By the 13th century the O'Donnells rose to dominance among the septs of Cenél Conaill. (Co. Donegal).
Donegal, inhabited anciently by the Vennicnii and the Rhobogdii according to Ptolemy, and later formed the northern part of Eircael (or Eargal) which extended into Co. Fermanagh. O'Cannnon (O'Canannain) were kings of Cinel Conaill here until the O'Donnells broke their power in the 13th century. The O'Donnells were descended from Conall Golban, and hence the territory attained the name Tyr Connell. The name of the county is derived from 'Dun na nGall' meaning fort of the foreigner because Donegal town was a Viking stronghold in the 9th century.
By the 13th century the O'Donnells rose to dominance among the septs of Cenél Conaill, the O'Gallaghers becoming the leaders of the O'Donnell calvary.
1, 2,