Complex sentence: Tudur Hen was not the first member of the family to be named Tudur: he was preceded by his uncle, Tudur ab Ednyfed, who had been in the service of the previous Prince of Wales, Dafydd ap Llywelyn.
Split into simpler sentences: Tudur Hen was not the first member of the family to be named Tudur. He was preceded by his uncle, Tudur ab Ednyfed, who had been in service to the previous Prince of Wales, Dafydd ap Llywelyn.