In the Stanzas of the Graves, Dywel's final resting place is given as "Caewaw" or "Caeo", a commot in south-west Wales. The englyn extolls Dywel's bravery on the battlefield.
The Grave of Dywel, the son of Erbin, is in the plain of Caewaw
He would not be a vassal to a king;
Blameless, he would not shrink from battle.
Sources
A. O. Jarman (gol.), Llyfr Du Caerfyrddin (Cardiff, 1982)
eto (gol.), Ymddiddan Myrddin a Thaliesin (Cardiff, 1951)