Inishowen (Irish: Inis Eoghain, meaning 'island of Eoghan') is a peninsula in the north of County Donegal in Ireland. Inishowen is the largest peninsula on the island of Ireland.
The Inishowen peninsula includes Ireland's most northerly point, Malin Head. The Grianan of Aileach, a ringfort that served as the royal seat of the over-kingdom of Ailech, stands at the entrance to the peninsula.
Tír Eoghain (meaning Land of Eoghan), also known as Tyrone, was a kingdom and later earldom of Gaelic Ireland, comprising parts of present-day County Tyrone, County Armagh, County Londonderry and County Donegal (Raphoe). The kingdom represented the core homeland of the Cenél nEógain people of the Northern Uí Néill and although they ruled, there were smaller groups of other Gaels in the area. One part of the realm to the north-east broke away and expanded, becoming Clandeboye, ruled by a scion branch of the O'Neill dynasty. In one form or another, Tyrone existed for over a millennium. Its main capital was Dungannon, though kings were inaugurated at Tullyhogue Fort.
Upon its foundation in the 5th century, Tyrone was a sub-kingdom of the larger Aileach, which represented the powerbase of the Uí Néill (descendants of Niall of the Nine Hostages) in the north of Ireland. The territory of Eoghan mac Néill was initially based in Inishowen and expanded out from there under his descendants. Periodically, during the time of Aileach, the leaders of Tyrone established themselves as High Kings of Ireland, providing in total of thirteen High Kings from the 6th to the 10th centuries. The first was Muirchertach mac Muiredaig and the last from this period was Domnall ua Néill. Three later Tyrone claimants to the High Kingship were Domnall Ua Lochlainn and Muirchertach Mac Lochlainn in 12th century and finally Brian Chatha an Dúna O'Neill in the 13th century.
Lough Foyle, sometimes Loch Foyle (Irish: Loch Feabhail, meaning 'Feabhal's loch' or "loch of the lip"), is the estuary of the River Foyle, on the north coast of Ireland. It lies between County Londonderry in Northern Ireland and County Donegal in the Republic of Ireland. Sovereignty over the waters has been in dispute since the partition of Ireland and the establishment of the Irish Free State in December 1922.
Lough Swilly (Irish: Loch Súilí, meaning 'lake of eyes') in Ireland is a glacial fjord or sea inlet lying between the western side of the Inishowen Peninsula and the Fanad Peninsula, in County Donegal. Along with Carlingford Lough and Killary Harbour it is one of three glacial fjords in Ireland.
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.