Claim: Gwenddoleu ap Ceidio died at the Battle of Arfderydd, a battle with no written record.
Evidence: The Battle of Arfderydd (also known as Arderydd) was fought, according to the Annales Cambriae, in 573. Annales Cambriae (Latin for The Annals of Wales) is the title given to a complex of Cambro-Latin chronicles compiled or derived from diverse sources at St David's in Dyfed, Wales. The earliest is a 12th-century presumed copy of a mid-10th century original; later editions were compiled in the 13th century.