Kings of Ailech in the context of "O'Neill dynasty"

Tyrconnell (Irish: Tír Chonaill, meaning 'Land of Conall'), also spelled Tirconnell and Tirconaill, was a kingdom of Gaelic Ireland. It is associated geographically with present-day County Donegal, which was officially named County Tirconaill between 1922 and 1927. At times it also included parts of County Fermanagh, County Sligo, County Leitrim, County Tyrone and County Londonderry at its greatest extent. The kingdom represented the core homeland of the Cenél Conaill people of the Northern Uí Néill and although they ruled, there were smaller groups of other Gaels in the area.

From the 5th century founding of Cenél Conaill, the tuatha was a sub-unit of the larger kingdom of Ailech, along with their Cenél nEógain cousins, fellow descendants of Niall of the Nine Hostages. Their initial ascent had coincided with the decline of the Ulaid, whose kingdom of Ulster receded to the north-east coast. In the 12th century the kingdom of Ailech split into two sovereign territories and Cenél Conaill became Tír Chonaill under the Ó Domhnaill (O'Donnell) clan. It was the location of fighting during the Nine Years' War (Ireland) at the end of the 16th century. It continued to exist until the 17th century when it was incorporated into the English-ruled Kingdom of Ireland following the Flight of the Earls.

The Grianán of Aileach (/ˌɡriːnən əv ˈæljə(x)/ GREE-nən əv AL-yə(kh); Irish: Grianán Ailigh [ˌɟɾʲiənˠaːnˠ ˈalʲiː]), sometimes anglicised as Greenan Ely or, locally, as Greenan Fort, is a hillfort atop the 244 metres (801 ft) high Greenan Mountain at Burt on the Inishowen Peninsula in County Donegal, Ireland. The main structure is a 19th-century reconstruction of a stone ringfort, thought to have been built by the Northern Uí Néill, in the sixth or seventh century CE; although there is evidence that the site had been in use before the fort was built. It has been identified as the seat of the Kingdom of Ailech and one of the royal sites of Gaelic Ireland. The wall is about 4.5 metres (15 ft) thick and 5 metres (16 ft) high. Inside it has three terraces, which are linked by steps, and two long passages within it. Originally, there would have been buildings inside the ringfort. Just outside it are the remains of a well and a tumulus.

By the 12th century, the Kingdom of Ailech had become embattled and lost a fair amount of territory to the invading Normans. According to Irish literature, the ringfort was mostly destroyed by Muirchertach Ua Briain, King of Munster, in 1101.