Kingdom of Dumnonia

An ancient kingdom that existed in the southwestern region of Britain during the early medieval period. It was one the Celtic Brittonic kingdoms that emerged after the Roman withdrawal from Britain in the fifth century AD. The territory of Dumnonia roughly corresponds to present-day Devon and Cornwall in England. Its most westerly potion being known as Cornubia to the Romans.

In the sixth century, it was apparently ruled by a King Constantine, who becomes Arthur’s successor according to Geoffrey of Monmouth.

History of the Kingdom of Dumnonia

Dumnonia’s people were Celts, part of the Brittonic-speaking population that inhabited much of the island of Britain before and during the Roman period. The Celtic Britons shared cultural and linguistic connections with other Celtic groups in Ireland, Scotland, and Wales.

Dumnonia was named after the Dumnonii, a Celtic tribe that inhabited the region even before the formation of the kingdom. The Dumnonii were known for their trading and seafaring abilities, and their territory was rich in mineral resources and agricultural land.

Before the Anglo-Saxon migrations, Dumnonia was under Roman rule as part of the Roman province of Britannia. Roman influence can still be seen in some of the region’s archaelogical remains, including Roman towns and villas. After the Roman withdrawal, Dumnonia became an independent kingdom with its own kings or rulers. It maintained its sovereignty and cultural distinctiveness despite external pressures from other neighboring Anglo-Saxon kingdoms, such as Wessex.

Christianity was established in Dumnonia during the early medieval period. Several Celtic saints, such as Saint Petroc, Saint Piran and Saint Nectan, are associated with the region and played a role in spreading Christianity.

The borders of Dumnonia were fluid and subject to changes due to both internal and external factors. Over time, the kingdom faced challenges from the expanding Anglo-Saxon kingdoms, particularly Wessex, which gradually encroached on Dumnonian territories. By the ninth century, Wessex, under the leadership of King Egbert, had extended its control over much of Dumnonia, and the kingdom effectively became integrated into the Anglo-Saxon realm.

De Excidio et Conquestu Britanniae | Gildas, c. 540