Ifor Williams identified eleven of the medieval poems ascribed to Taliesin as possibly originating as early as the sixth century, and so possibly being composed by a historical Taliesin. The bulk of this work praises King Urien of Rheged and his son Owain mab Urien, although several of the poems indicate that Taliesin also served as court bard to King Brochfael Ysgithrog of Powys and his successor Cynan Garwyn, either before or during his time at Urien's court. Some of the events to which the poems refer, such as the Battle of Arfderydd (c. 573), are referred to in other sources.