The Life of St. Cadoc by Lifris (c. 1100) portrays Brychan fighting Arthur, Cai and Bedivere because of King Gwynllyw of Gwynllwg's abduction of his daughter St. Gwladys from his court in Talgarth.
Saint Gwladys ferch Brychan or St Gladys (Latin-Claudia), daughter of King Brychan of Brycheiniog, was the queen of the saint-king Gwynllyw Milwr and the mother of Cadoc "the Wise", whose vita may be the earliest saint's life to mention Arthur.
AD), the first king of Glywysing, when the kingdom was divided between three of his sons, Pawl, Gwynllyw and Mechwyn.