The Irish Annals record for the yeare of our Lord 331, "The battle of Achadh Leithdheirg, in Fearnmhagh (Farney), was fought by the three Collas against the Ulstermen, in which fell Fearghus Fogha, son of Fraechar Foirtriun, the last king of Ulster, who resided at Eamhain. They afterwards burned Eamhain Macha, and the Ulstermen did not dwell therein since. They also took from the Ulstermen that part of the province extending from the Righe and Loch nEathach (Neagh) westwards. Colla Meann fell in this battle.

Airthir (Airtheara)

Fir Lí - Feara Li, or Fer Li, i.e. the men of Mag Lí, was located west of the River Bann in the barony of Coleraine, Co. Derry. The Book of Lecan notes that Fir Li (and Uí mac Uais) in Ulster extended from Bir (Moyola river) to Camus (south of Coleraine). The Moyola river was anciently the boundary between the Feara Li and the Húi Tuirtre.

The Fir Lí are noted as an Aighiallan people who came under the dominion of the Cenél Eóghain by the 9th century. Their neighbors appear to have been the Uí Tuirtre and factions of both groups are said to have been driven to the east of the Bann (into Ulidia) by the advance of Ua Cathain of the Cenél Éoghain. Another Airghiallan group, the Fir na Chraíbe, were also noted at an early date in the region west of the Bann. The sept of Ó Floinn (e.g. O'Lynn) became kings of Uí Thuirtre and Fir Lí by the late 12th century, and the territory name, Loch Inse Uí Fhloinn, is remembered in the name of the barony of Loughinsholin, in southwest county Derry. This was within the traditional territory of the Uí Thuirtre and Fir Lí, west of the Bann.

Dartraige - remembered in the barony of Dartree in west co. Monaghan, it was also referred to as Dartaige Coininnsi. The O'Boylan (Ó Baoighealláin) sept are cited as early kings of Darty (Dairtre) in Orghialla. O'Dugan mentions the Muinter Baoigheallain in his Topographical Poem. From the same stock as the O'Flanagans of Fermanagh, the territory of Ó Baoigheallain (O Boylan) during early medieval times, as lords of Airgialla, stretched from Fermanagh to Louth before being reduced by the MacMahons. There was also a Dartraige centered in Breifne.

Uí Cennfhada

Fir Lemna - or Uí Tuathail, Damine

Síl Duibthir - mentioned with Fir Leamhna and Uí Cremthainn as one of the Trí Tuatha of Airghialla. The sept of Ua Laithéin are noted as chiefs of Síl Duibtire in the 10th/11th century. O'Dugan (Poems) cites the tribe of Duibhthire, over the Clanna-Daimhin in Oirghialla, quite likely a reference to Síl Duibthir.

Fir Rois - Feara Rois, or Fer Rois, was located in south Airghialla.

Airtheara - was centered in Co. Armagh, about the eastern baronies of Orior. In earlier times the term Airthir (literally meaing 'east') may have included most of co. Armagh.