Dumnonia, a Latinised name, was a Brythonic kingdom that existed in Sub-Roman Britain between the 6th century CE and the 7th century CE in the more westerly parts of present-day South West England.
Cadbury Castle, Somerset, a possible early Dumnonian defensive site
King Doniert's Stone in Cornwall, believed to commemorate Donyarth, the last recorded king of the rump state of Dumnonia
Lostwithiel the Stannary Palace geograph.org.uk 571361
Cornwall is a ceremonial county in South West England. It is one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, Devon
Dumnonia
…present-day South West England. Its predecessor, the pre-Roman Dumnonii territory, was centred in the area of modern Devon, but also included modern Cornwall and part of Somerset; its eastern boundary was moved westward over time with the gradual expansion of the neighbouring Anglo-Saxon kingdom of Wessex…
The stamps and whim engine house at Wheal Coates geograph.org.uk 1476958
A walk on Bodmin Moor, Cornwall, 30 Sept. 2010 Flickr Phillip C