Arthur, describing his warriors’ exploits in an early Welsh poem, says
They fell by the hundred before Bedwyr the Fine-sinewed on the strand of Tryfrwyd, fighting with Garwlwyd [...]
This may be an allusion to the battle of Tribuit mentioned by Nennius.
Source
Pa gur yv y porthaur | Poem 31 of the Black Book of Carmarthen, probably c. 1100