Rhys ap Gruffydd
Einion o'r Porth married Susanna, a daughter of Rhys ap Gruffydd, the ruling prince of Deheubarth. The only named ruler of Gwrtheyrnion in historic manuscripts (other than the legendary Pascent) is an "Einion ap Rhys" who visited the king in 1175, and was Rhys ap Gruffydd's son-in-law; unless this "Einion ap Rhys" is really a bodged reference to Einion o'r' Porth, then he, his father, and the consequently distinct line of rulers in Gwrtheyrnion, are otherwise entirely unknown. In 1177, Rhayader Castle was built in Gwrtheyrnion by Rhys ap Gruffydd.