In the tenth and eleventh centuries, the O'Conalláin were Princes of Ui Laeghari, an extensive territory in the counties of Meath and Westmeath, where the High King of Ireland historically derived his seat at the Hill of Tara.
As a sept of the Northern Uí Néill, they claim descent from Niall of the Nine Hostages and his son Conall Gulban, both High Kings of Ireland.
Their kingdom was known as Tír Conaill, with their powerbase at Mag Ithe in the Finn valley, however they gradually expanded to cover what is now counties Donegal and Fermanagh.
Related dynasties descended through Conall Cremthainne and Diarmait mac Cerbaill included the Síl nÁedo Sláine, the kings of Brega, descended from Colmán Már's youngest brother Áed Sláine and the Kings of Uisnech, among others, belonging to Clann Cholmáin.
[2][3] Several prominent figures originating from the Tir Conail kingdom included Maximilian, Count von Tyrconnell.