Complex sentence: The first community failed because of the intervention of Hugh de Mortimer, Earl of Hereford but in 1176 the Lord Rhys of Deheubarth reestablished the Abbey on land given by Cadwallon ap Madog.
Split into simpler sentences: The first community failed because of the intervention of Hugh de Mortimer, Earl of Hereford. In 1176 the Lord Rhys of Deheubarth reestablished the Abbey on land given by Cadwallon ap Madog.