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.