As I noted previously, I prefer to start Pendragon games in the late 5th century… either during Aurelius Ambrosius’s campaign to unseat Vortigern or during the reign of Uther. In doing so I like to use older maps of Britain, particularly those that show the Roman settlements and roads, along with the tribal divisions of the island.
The reason I focus on the Roman and tribal elements is that the native Britons would have strong ties to their tribes, and would primarily identify as members of those tribal groups. In fact, a recent study shows that Britons still live roughly in the same areas they did in the 6th century! At the same time, the Romans occupied Britain to some extent from 43 AD until 410 AD. During that time, their roads, settlements, fortifications, trade arrangements, and tribal relations surely made a huge impact upon the people and landscape of Britain.
The Votadini tribe, for example, lived under the direct rule of Rome between Hadrian’s Wall and the Antonine Wall from 138-162 AD. When the Romans withdrew behind Hadrian’s Wall in 164 AD, they left the Votadini as a client kingdom, a buffer zone against the Picts in the north. They maintained client status until the Romans pulled out of Britain in 410 AD. Through a series of linguistic changes, the Votadini became known as the Gododdin, and maintained a kingdom until their defeat by the Angles c.600 AD.
Here are some of those maps: