Coel Hen died in 426, and Britannia Secunda was split between his eldest sons (Coelings). Ceneu took the heartland around the capital at Caer Eborac (modern York) and the northwest districts to the Solway; Garban, took the northeast district of Bryneich, the old Votadini tribal lands. Coel’s daughter, Gwawl, married Cunadda of Manau Gododdin, a mormaer whose Votadini warriors fought the Picts. Cunadda also campaigned in northern Wales, defeating the Irish raiders and founding the Kingdom of Gwynedd. Like Vortigern, Ceneu brought in bands of Anglian warriors to fight the raiding Picts and Scots. He settled these in Deifr, immediately north of the Humber.
When Ceneu died in 444, his eldest sons split the kingdom in two... 1
Another source shows "Saint Ceneu ap Coel" having died in 470, after "having attended the coronation of the great King Arthur." This is drawn from Geoffrey of Monmouth's History of the Kings of Britain and therefore can be taken with a grain of salt. 2