Bartrum's "Welsh Classical Dictionary". The chief authority for the life of Peibio is the Book of Llandaf. In charters associated with St. Dubricius he is said to be son of Erb (BLD 72, 76), and the following sons are mentioned: Cynfyn, Cinust and Guidci or Guoidci. His wife was the daughter of a king named Constantinus (BLD 72). Peibio is described as king of Ergyng (BLD 78, 163). The Book of Llandaf contains three charters in which Peibio occurs. In one of these (72a) Dubricius occurs as the first clerical witness with several of his disciples. The other two (72b, 73a) only mention disciples of Dubricius as clerical witnesses.