He was Christened of the tribe Rhys ap Tewdwr.
[citation needed] Rhys ap Gruffydd was the uncle of Einion.
[1][2] Einion aided King Henry II of England in 1158 in taking and destroying all the castles of Caredigion, gaining much in spoils of war.
[3][4][5] He was the captain of the king's bodyguard and the leader of the procession that raided the castles.
[citation needed] Einion was killed in 1163 by orders of Roger de Clare, 2nd Earl of Hertford.