 but the name is preserved as the tuath  of Tir Ollíol (Tirerril).The Lords of Tir Olioll were Mac Donnchadha of the Uí Briúin Aí a branch of the Mac Díarmada of Moylurg (Magh Luirg).The Mac Donagh (Mac Donnchadha) surname originates from Donnchadh, son of Tomaltach na cairge (of the rock) ua Mac Diarmata, who was King of Moylurg 1197-1207.