South-west England was never as ‘Romanised’ as south-eastern England, and as Roman authority broke down, the region returned to an older way of life. A British society of local leaders and small settlements lasted for at least a century. Urban life rapidly declined and public buildings like forums and baths fell into disuse. In the centre of Exeter farming was taking place even in the late 4th century AD and the poor quality of surviving pottery elsewhere suggests that people were leading meaner lives.

The region was too far west to suffer much from the early Saxon takeover. Many hillforts were reoccupied, some as fortifications against the Saxons, but others as the centres of settlements. Iron Age defences at South Cadbury fort (in modern Somerset) were refurbished in the later 5th century and a wooden hall was erected. Fragments of Mediterranean amphorae (wine jars) found there suggest a wealthy occupant, probably a native aristocrat, and point to continuation of the traditional trade with Gaul.

The British kingdom of Dumnonia (modern Cornwall, Devon and west Somerset), protected to the east by the Fosse Way and the great forest of Selwood (on the boundary between modern Wiltshire and Somerset), only began to fall to the West Saxons in the early 7th century. Cornwall remained independant until the 9th century.