Íomhaor Mág Tighearnán, the Second (anglicised Ivor McKiernan) was chief of the McKiernan Clan and Baron or Lord of Tullyhunco barony, County Cavan from 1258 until his death c.1269.
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Ancestry
Íomhaor was the son of Tighearnán who was son of Duarcán the First, son of Íomhaor the First, son of Gíolla Chríost, son of Amhlaoibh, son of Tighearnán, the founder of the clan.
Chieftainship
On the death of the previous chief, Macraith Mág Tighearnán, Íomhaor took the chieftaincy and resided in the castle of Croaghan of the Cups (Irish- Cruachan O'Cúbhrán), besides the modern town of Killeshandra. Macraith had been killed in 1258 by Domnall O'Ruairc (son of Conchobar son of Tigernán), king of Breifne from 1258 to 1258, and the McKiernans soon took their revenge.
The Annals of the Four Masters for 1260 state-
Donnell, son of Conor, son of Tiernan O'Rourke, was treacherously slain by the inhabitants of Tealach-Dunchadha; and Murtough, his brother, was afterwards slain by Hugh O'Conor. Art Beg, son of Art O'Rourke, was also slain by Hugh O'Conor.
The Annals of Connacht for the year 1260 state-
Domnall son of Conchobar son of Tigernan O Ruairc, king of Brefne, was craftily killed by the Tellach Dunchada. Muirchertach his brother was then killed by Aed O Conchobair.
The Annals of Loch Cé for the year 1260 state-
Domhnall, son of Conchobhar, son of Tighernan O'Ruairc, i.e. the king of Breifne, was killed by the Teallach-Dunchadha by deceit; and Muirchertach, son of Conchobar, his other brother, was afterwards killed by Aedh O'Conchobhair.
The Annals of Ulster for 1260 state-
Domnall, son of Concobur, son of Tigernan, was killed by the Tellach-Dunchadha.