Aergol Lawhir

King of Dyfed in the 5th – 6th centuries A.D. 
Aergol was known to be an enemy of King Cynan Garwyn of Powys, and they clashed at Crug Dyfed. He conquered the Ystrad Tywi around the late 400s, which was why he was given the name “Long-Hand.”
Also: Aergol Longhand