Although disagreeing on many other aspects, both kernowsceptic and kernocentric historians unite in accepting a kingdom of Dumnonia as a clear and obvious fact. Dumnonia appears as a fully functioning kingdom, replete with kings and courts and operating for some centuries after the ending of Roman rule around 410. Its existence is endlessly and uncritically repeated while it sailed serenely down the centuries until rudely scuppered by the English at some point from the late seventh century onwards.
However, a political unit called Dumnonia could well be a myth. Once the Romans had departed, explicit references to the Dumnonii are rare and those to an entity called Dumnonia rarer still. Nobody in the south-west of Britain explicitly described themselves as ‘Dumnonian’ in the period from 400 to 800; no inscribed stones are found asserting a Dumnonian origin or identity. There are no credible king lists. It looks more like a vague regional description. English sources do not mention Dumnonia or Dumnonians by name. More significantly, the terms are absent from Welsh writings. The Welsh Annals make explicit references to Welsh kingdoms from the sixth century but there is no mention of Dumnonia, just Cornwall.
The kingdom of Dumnonia is as wisp-like as Arthur. Far from glittering reality, it appears to be shimmering illusion.
Let’s adopt a more kernowcentric interpretation. Constantine in the 530s ruled over a place known to contemporaries such as Gildas as Dumnonia. Dumnonia was the name of a territory, derived from a people – the Dumnonii – and a reminder of the Roman Empire at a time when British elites were keen to don the garb of Romanitas. Constantine was a member of a shifting group of elite families that had fastened onto the power associated with the prestige goods being imported from the Mediterranean. The centre of gravity of this kingdom was found in the west, with a periodic high-status presence at Tintagel.
Dumnonia in practice meant a Greater Cornubia. The heartland of this kingdom lay west of the Tamar, with only fragile links to the east. The archaeological evidence from the sixth to the eighth centuries, the relative absence of Mediterranean imports inland east of the Tamar, the lack of pottery production in Devon, the paucity of high status sites there, the decay of Exeter, all point to a distinction between the west and the east. Cornwall was not created out of the rump of Dumnonia, as is claimed. Quite the opposite; Devon was in practice the ‘tail-end’ of a Greater Cornubia that experienced its high point in the period from 450 to 550.
In the second half of the sixth century the power of this ruling elite collapsed. Any hold over the extensive territory east of the Tamar then became weaker and was exercised in name only. Even the possibility of a coherent, uniformly administered ‘Dumnonia’ faded. The reach of those aspiring to the title of king shrank. For all intents and purposes during the seventh century what remained of the kingdom of Dumnonia shrivelled westwards into its core or might in practice have disappeared. Yet, as Dumnonia was primarily an external categorization, outsiders still sometimes referred to the region as Dumnonia.
By Aldhelm and Gerent’s time around 700 ‘Dumnonia’ was a term usually restricted to what later became Devon. Gerent might still have claimed some sort of nominal overlordship over Dumnonia/Devon. The problem was that by this time, perhaps from the 680s, the English were beginning to nibble away at territory in the far east. Devon/Dumnonia by the end of the seventh century was effectively contested territory and continued to be so until the 820s.
(Adapted from my Cornwall’s First Golden Age, chapter 2.)