The Caermarthen is a work by Biracas of Diedne written in 992. The tome is a collection of the folk lore and legends of Wales. A renowned and powerful Diedne magus, Biracas disappeared just before the start of the Schism War and most of his works disappeared with him. The book is a tractatus on Area Lore: Wales, written in Latin, with a quality of 13.