sentences:  His work is often compared to that of his contemporary, Muirchú, who wrote "Vita Sancti Patricii" (Life of St. Patrick).Historians have dated Tírechán’s work to the second half of the seventh century based on the date of his tutor’s death (656) and references in his works to events known to have occurred in that period—e.g., plagues, ecclesiastical controversies, and the warring of Irish dynasties.