After the Battle of Penn Hill of 665, at which almost all of the rulers of four southern Anglo-Saxon kingdoms were killed or captured, the great alliance of the Britons was able to reoccupy much of the southern half of the island without facing much resistance. East Anglia, Essex and Kent survived intact, albeit badly weakened, but the powerful states of Mercia and Wessex imploded and were reduced to a shell of their former selves. The remaining Anglo-Saxon territories in eastern Albion came to be known as Lloegyr.
Much of the conquered territory was divided between the powerful states of Powys and Dyfnaint, but the new kingdom of Gadwfellwn was also set up on the territory of the old Catuvellaunian tribe. The rump of Wessex submitted to Dumnonian overlordship, and Lindsey took the opportunity to attain full independence from Mercia.
English Northumbria survived, and with its manpower swelled by refugees from the south it soon managed to conquer its British neighbours in Rheged and Strathclyde. Most of Deira was lost to in 696 after the Battle of Loidis, but the remaining Angles in the north remained strong.
Most of former Deira was formed into a Powysian client kingdom centered at Caer Ebrauc, which achieved independence from Powys in 730 after a bried civil war. A smaller part, based at Caerlleon Fawr, came under the rule of Gwynedd and achieved independence in 735, thus establishing the last of the nine British kingdoms. Although their borders often changed, and smaller kingdoms could sometimes come under the dominion of larger ones, Ebrauc, Caerlleon, Gwynedd, Powys, Demet, Gwent, Gadwfellwn, Dyfnaint and Cernyw remained mostly stable for the next century and a half.
Regular Viking raids began in the late 8th century, but when the Great Heathen Army arrived from Norway in the 860s it found Albion utterly unprepared. With a few years Ebrauc, Caerlleon, Powys and Gwent had all fallen to Danish and Norse warlords, along with most of Lloegyr, and Dyfnaint only just managed to fight them off. Soon, though, Dyfnaint was on the offensive against the Danes, and by the end of the century had reconquered southern Powys and Gwent and was recognised as overlord by all the other remaining British kingdoms.
By 927 King Hywel conquered Ebrauc and was proclaimed High King of the Britons, an act which was later seen as having founded the Kingdom of Prydain. Although Ebrauc was later lost again and was not retaken before the Arvorian conquest, the remainder of Prydain consolidated itself over the next two centuries into a single kingdom.
For events after this date, refer to the histories of Prydain and Albion.