Until the early 5th century Dumnonia, along with the rest of southern Albion, was a part of the Roman diocese of Britannia. The last Roman troops withdrew in 407 and most of the civilian administration had been expelled by 409. Conomor ap Tutwal was the first ruler of the Dumnonii to renounce his Roman administrative office and set himself up as an independent king. The rule of the Dumnonians finally came to an end with the Arvorian conquest. Prydain entered into personal union with Arvor and, briefly, Lyonesse. This union came to and end after the end of the Jersiais.