Bartrum's "Welsh Classical Dictionary". He is mentioned in the Book of Llandaf as the father of Peibio, king of Ergyng (BLD 72, 76). His wife is said to have been a daughter of a certain king Custennin (Constantinus, Custenhin) (BLD 72a). A charter in the Book of Llandaf (BLD 75) mentions Erb, king of Gwent and Ergyng, as the donor of Cil Hal to Dubricius. Wendy Davies dates the charter c.555 (LlCh p.94), but Dubricius probably died in about 525. In the pedigrees in JC 10 we find "Pibiawn glawrawc m. Arbeth," after which there seems to be some corruption. But he occurs again in a pedigree of kings of Glywysing as the father of Nynnio: "Nynnyaw m. Erb m. Erbic" (JC 9, similarly in AB 15). That the same Erb is meant is confirmed by the tradition of two brothers Nynnio and Peibio.