According to the Annals, Nial MacLochlainn, the father of Muirchertach died in 1119 A.D. and was 28 years old. 1119 [AU] Niall, son of Domnall Ua Lochlainn, royal heir of Ailech and of Ireland and paragon of Ireland for form and for sense, for generosity and for erudition, fell by the Cenel-Maoin, in the 28th year of his age, on Monday and on the 10th of the moon and on the feast of the Three Innocent Children, the 18th of the Kalends of January. So that would make him born in about 1091. His father, Domnall MacLochlainn, died in 1121, and was 73 years old, making him born in about 1048. (Clann Lochlainn).