A Brythonic kingdom in southwestern Britain (Cornwall, Devon, and parts of Somerset/Dorset) that resisted Anglo-Saxon expansion for centuries; gradually conquered by Wessex through Egbert's campaigns (813-822), with a rump Cornish kingdom surviving until the last known Cornish king Donyarth died in 875 and Athelstan fixed the Tamar as Cornwall's border by 936.
Gradually conquered by Wessex; the insular core fell to Egbert's campaigns of 813-822, and the rump Cornish kingdom ended with the death of King Donyarth in 875, though a distinct Cornish identity persisted under English overlordship.
The atlas holds 2 border frames for Dumnonia — the shape you scrub through changes in 410 · 505.
Accessible modern account of Britain's fifth- to seventh-century kingdoms in the age of Arthur.