(Chwedyl) Gereint/Geraint mab/vab/fab/fil(ius) Erbin ((Legendary) Gereint/Geraint, son of Erbin), from Llyfr Du Cærfyrddin (Black Book of Cærmarthen) and Llyfr Coch Hergest (Red Book of Hergest). Ninth/Tenth/Eleventh Century AD, originally c AD 480:

‘Gerein fil. Erbin (MS. Peniarth 1 from Llyfr Ddu Caerfyrddin, pp71-73)’ at Mary Jones, 15 June 2014.
http://www.maryjones.us/ctexts/bbc22w.html

‘Geraint son of Erbin (in Black Book of Carmarthen, XXII and Red Book of Hergest, XIV)’ at Mary Jones, 15 June 2014.
http://www.maryjones.us/ctexts/bbc22.html