The Irish annals contain little reliable information on his life, and the surviving record shows signs of retrospective modification.
His mother, "obviously legendary" according to Thomas Charles-Edwards, was said to be Erca, daughter of "Lodarn, king of Alba".
[1] The annalistic entries for Muirchertach span 50 years, from 482 to his death in 534, using various names, including Mac Ercae, so that it is more than likely that two or more people have been confused in the annals.
The 12th-century Middle Irish tale Aided Muirchertaig Meic Erca is an account of Muirchertach's supernatural death.
Here Muirchertach dies in the House of Clettach, drowned in a vat of wine, burned by fire, and crushed by a falling roof beam, near Brú na Bóinne, beguiled by the illusions of the otherworldly maiden Sín into believing that he is being attacked by Túathal Máelgarb.