Nightbringer | The Arthurian Online Encyclopedia


Kingdom of Dumnonia

An ancient kingdom that existed in the southwestern region of Britain during the post-Roman and early medieval periods. 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.

Dumnonia | History

Roman Period | 1st – 5th centuries
The territory that would later become Dumnonia was part of the Roman province of Britannia. The region was known for its significant Roman influence, and there were Roman towns and settlements in the area. The Dumnonii, a Celtic people, inhabited this region during the Roman occupation. The Dumnonii were known for their trading and seafaring abilities, and their territory was rich in mineral resources and agricultural land. The Celtic Britons shared cultural and linguistic connections with other Celtic groups in Ireland, Scotland, and Wales.

Post-Roman Period | 5th century
With the decline of Roman rule in Britain in the early fifth century, the Dumnonian region witnessed changes in governance and political structures. As the Roman legions withdrew, various Celtic and Germanic groups vied for control of different territories.

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.

Emergence of Dumnonia | 6th – 7th centuries
Dumnonia emerged as a distinct kingdom in the post-Roman period, encompassing parts of what is now Cornwall, Devon, and parts of Somerset and Dorset. The Dumnonii likely played a role in establishing this early medieval kingdom. The kingdom of Dumnonia became independent with its own kings or rulers. It maintained its sovereignty and cultural distinctiveness despite external pressures.

Trade and Cultural Exchange
Dumnonia, situated in the southwestern corner of Britain, had significant maritime connections and engaged in trade with other regions. The kingdom benefited from its coastal position and likely had cultural exchanges with neighboring Celtic regions.

Anglo-Saxon Invasions | 7th century
Like many other parts of Britain, Dumnonia faced incursions by Anglo-Saxon groups during the seventh century. The Anglo-Saxons sought to expand their territories, leading to conflicts with indigenous Celtic kingdoms. Dumnonia resisted the Anglo-Saxon invasions, and its rulers attempted to maintain their independence.

Kingdom’s Decline and Integration into Wessex | 8th – 9th centuries
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. The process of integration and assimilation likely involved both political and cultural factors.

De Excidio et Conquestu Britanniae | Gildas, c. 540