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Celtic Kingdoms of the British Isles

Celts of Britain


Dumnonii (Britons)

FeatureIt was the Romans who coined the name 'Gaul' to describe the Celtic tribes of what is now France and Belgium, quite possibly based on an original form of the word 'Celt' itself (see feature link). When it came to the Celts of Britain, the name of the islands itself was used: Prydein (Latinised as Prettania or Britannia). Its collective people were Britons, although not all of them were Celts, let alone the same 'type' of Celts. Successive waves of immigration had left a vague mix of Bell Beaker folk, Urnfield proto-Celts, Hallstatt and La Tène waves, and Belgae, the latest arrivals. By the first century BC these latter people dominated the south and east of the isles.

MapBritain's long 'tail' of territory in the south-west of the island was occupied by the Dumnonii. By the first century BC, that territory was formed of two distinctive halves, one on either side of the River Tamar, with the Dumnonii being to the east of the river. The River Exe generally (but perhaps not permanently) formed a border with the neighbouring Durotriges. To the north of them, across the Bristol Channel, were the Silures, while across the English Channel were the Cariosvelites, Redones, and Venelli. The Cornovii of modern Cornwall to the west of the Tamar may or may not have been a sub-division of the Dumnonii, or even a separate tribe (see the map of most of Europe's tribes around the first centuries BC and AD to view the locations of these tribes in relation to all other Celts).

The Dumnonii were a people with strong traditions which reached back unmixed - perhaps unusually - into the Bronze Age. They seemingly predated the general arrival in Britain of Celts of the Halstatt C culture, although it cannot be stated with any certainty that there was no contact with the very earliest proto-Celtic arrivals of the Urnfield or that the Dumnonii were not Urnfield people themselves. Peculiarly, perhaps, intermarriage between other tribes was noted as being uncommon - although this would not be quite so peculiar if they still saw the 'easterners', the neighbouring Durotriges and Dobunni especially, as being somehow 'foreign'.

Despite this apparent reluctance to embrace newer arrivals in the country, the Dumnonii were still notably friendly to strangers, and they also benefited from the Cornish tin trade. This meant regular visits by traders from the length and breadth of the Mediterranean, who also brought with them strange customs and trade goods which must have enhanced Dumnonii life and culture, while possibly enhancing the sense of 'differentness' with neighbouring British tribes. The tin trade may have begun as early as the sixteenth century BC, with visits by Minoans and then Phoenicians being likely, so that the occupants of the south-west had a long tradition of working and trading with more advanced cultures. The tin trade had faded out by the first century AD, but whatever cultural influences the tribe may have absorbed from earlier traders, they certainly seemed to take none from the Romans.

The Dumnonii name probably means 'the masters', or 'the dominators', or even 'the lords'. It appears to derive from a more militarily and socially-dominant (unrecorded) Gaulish word which is cognate with the Latin 'dominus' ('master' or 'owner'). It is a militaristic name for a tribe which dominated Britain's south-west. However, sub-groups within the tribal collective may have named themselves after the god they followed. This is an especial possibility with the Cornovii.

In the Devonian core of their territory the Dumnonii appear to have used hill forts of the common British type. Across the Tamar, however, these virtually disappear and their place is taken by fortifications which are very similar to those in Brittany and Spain. This could support the idea that the Cornovii were a separate tribe - one which was probably conquered by the Dumnonii for control of the tin trade. Whatever the truth of this supposition, the Cornovii may indeed have had different (and probably earlier) origins which could have been similar to those of the southern Irish of Munster.

The Dumnonii were noted by Ptolemy in his Geographia as having three [major] settlements, the first being Tamara, clearly located on the River Tamar (Latin 'Tamarus'), probably the original Plymouth. The second was Uxella, from the Brythonic *iskā, meaning 'water' and with what appears to be a diminutive suffix '-el', providing a meaning of 'little water'. This was located at Uxella Estuarium - the 'Uxella' being the modern River Axe.

This 'Axe' is sometimes claimed as the one between Wells and the Bristol Channel in Somerset, with the settlement being at Bridgwater, but is more likely to be the Axe of Somerset, Dorset, and Devon, rising in Beaminster in Dorset, running through Axminster, and exiting into the English Channel at Axmouth in East Devon (the most likely location of an Uxella 'Estuary'). Either choice would place the first century AD Dumnonii well to the east of the River Exe and seemingly into Durotriges territory, but how recent a development this may have been is unknown. The third settlement was Voliba (location unknown). However, the tribe does not appear to have had a single dedicated tribal centre.

Although under nominal Roman control between AD 44 and the late fourth century, the Dumnonii probably exercised a certain amount of self-government in their own lands (and may have been almost entirely self-governed during the period. Their nobles would have retained their lands and position, and the hereditary chiefdom may well have remained within the same family group, given that there may have been little conflict on offer to dislodge them.

The Romans clearly found the Dumnonians to be fierce in their resistance to invasion, and it is thought that the two sides reached an understanding whereby the Dumnonians would be cooperative clients if the Romans left them alone. Strangely, Ptolemy is the only ancient author to record them, so it does seem that official Roman interaction with the tribe was kept to a minimum, largely leaving them outside 'civilised' interest. Archaeology is showing, though, an increasingly detailed presence of traders from the empire.

FeatureAccording to a tradition which was first written down by Nennius (as far as surviving records go, and see feature link for more), and then Geoffrey of Monmouth, the Dumnonians were descended from Corineus and his people, themselves the descendants of Trojan refugees and fellow arrivals with Brutus, the legendary first high king of Britain. Corineus was the eponymous founder of Cornubia (Cornwall) and wore one of the 'Three Coronets of Britain'.

Ancient Britons

(Information by Peter Kessler, with additional information by Edward Dawson, from The Oxford History of England: Roman Britain, Peter Salway, from Atlas of British History, G S P Freeman-Grenville (Rex Collins, London, 1979), from Roman Britain: A New History, Guy de la Bédoyère, from Geography, Ptolemy, from History of the Kings of Britain, Geoffrey of Monmouth, from On the Ocean, Pytheas of Massalia (work lost, but frequently quoted by other ancient authors), and from External Links: Dewnans Celtic Devon (dead link), and England's western-most Roman town uncovered (BBC News), and Roman Britain, and Plymouth Local History, and New finds beef up case for redrawing map of Roman empire (The Guardian).)

4th century BC

The Castle Dore hill fort near Fowey in Cornwall is constructed. It consists of a circular bank and a ditch, with a second enclosure inside. Both enclosures have an entrance to the east, away from the prevailing winds. Thought to serve as an animal enclosure, it is first excavated by archaeologists between 1936-1937.

Castle Dore
The remains of the Castle Dore hill fort are clearly seen from the air, with the fort being constructed by the inhabitants of Cornwall in this period, possibly even before the Cornovii had formed a tribe of this name

Much of the surrounding valley is flooded at this time, and the view from the fort is impressive. A small village may exist outside the eastern gate in the fort's early days. (The name - 'Dore' - is an odd one, seemingly the same core word as is contained in the tribal name Durotriges.)

c.325 BC

Pytheas of Massalia, a Greek geographer and explorer undertakes a voyage of exploration around north-western Europe. During his trip he visits Britain, which he names the Prettanic isles (spellings vary thanks to the translation from the original Greek, and the name covers all of the islands and Ireland too).

FeatureHe travels extensively, making notes of what he sees (see feature link), and also providing what may be the earliest written report of Stonehenge. He names the promontory of Kantion (land of the Cantii), the promontory of Belerion (land of the Cornovii), and Orkas (the Orkneys). Belerion is home to a civilised people who are especially hospitable to strangers, apparently due to their dealings with foreign merchants who are involved in the tin trade.

Belerion may be home to the people of the Celtic god, Bel. This name occurs in many tribal names among the Celts, including the Bellovaci in Gaul, Belgites in Illyria, Velabri in Ireland, and of course the various Belgic tribes.

Ptolemy's map of Britain
The details recorded by Pytheas were interpreted by Ptolemy in the second century AD, and this 1490 Italian reconstruction of the section covering the British Isles and northern Gaul shows Ptolemy's characteristically lopsided Scotland at the top

In Cornwall there is a unbroken tradition of celebrating Bel's day (Beltane) with large fires, cattle being driven between two such fires, and young men jumping the flames, but just when the people stop naming themselves after their god and become the Cornovii (whether this is derived from the name of a god or the tribe's location) is not known. Most likely, it seems that the tribe overall is the Dumnonii, while local peoples use the name of their god or location to define themselves, and it may be one of these smaller groups which Pytheas meets and records.

AD 43

With the defeat of the Catuvellauni by soon-to-be Roman Governor Aulus Plautius and Emperor Claudius, part of the Dobunni appear to surrender themselves to Plautius by means of envoys.

Although the details available are very brief and contain no chronology, the Roman second wing under Vespasian invades Dorset. The Durotriges fight hard to retain their independence, and there are signs of violent attack at many hill forts. The Durotriges at Maiden Castle take the time to bury eight of their dead following the Roman attack (to be discovered by modern archaeologists). The Dumnonii role in the imperial invasion is unknown, and perhaps entirely unrecorded.

Map of Britain AD 10
By the end of the first century BC and the start of the first century AD, British politics often came to the attention of Rome, and the borders of the tribal states of the south-east were pretty well known (click or tap on map to view full sized)


During the Roman Governorship of Aulus Didius Gallus, the Romans build and occupy a legionary fort on a spur overlooking the River Exe, named Isca (a name which is taken directly from the common Celtic word for water, *iskā, and which still exists in use today as 'Exe'). In full, the Roman name is Isca et Legio Secunda Augusta.

Following the no-doubt disturbing arrival of the Romans, elements of the Dumnonii may flee to Ireland where a similarly-named tribe is later known to exist - the Fir Domnann, possibly with a relationship to the similarly-named Fir Bolg.

To the far north of Britain another tribe named the Damnonii exists, possibly also a colony of refugees from the south-west. The Romans themselves inhabit a settlement near St Austell in the territory of the Cornovii, which may be an ironworks. This is one of the very few instances of Romans venturing deep into the Cornish peninsula. They are known to provide guards for a few tin mines, but little else has generally been found by archaeologists.

A brand new discovery in 2010 in a greenfield site in Devon suddenly offers the chance of virtually doubling the amount of territory known to have been Roman-occupied within Dumnonii borders. A previously unknown Roman town appears to have existed several kilometres to the west of Isca, making it the most westerly of all major Roman sites outside of what is now Wales.

Roman Exeter
An artist's impression of the Roman settlement of Isca Dumnoniorum (Exeter), with 'Isca' coming from a Brythonic word for water which is still in use today (Exe)

Almost a hundred Roman coins are discovered, leading to further investigation which reveals a huge landscape, including at least thirteen round-houses, plus quarry pits and trackways covering at least thirteen fields, the first of its kind for the region, along with a possible cemetery. Much more work on the site is required.

c.60 - 65

The site of Isca's Roman baths are discovered by archaeologists in 1971. Due to a lack of funds the find is reburied under the cathedral green in Exeter in order to protect it. Built around AD 60-65 the baths are able to accommodate hundreds of bathers. Together, Isca's bathhouse and basilica are the largest set of Roman remains in the south-west of Britain. The baths include a large caldarium, or hot room, a trepidarium, or cold room, an expensive furnace house, exercise yard, and multiple service rooms.

c.75 - 80

The Roman legion based at Isca is withdrawn so that it can help in the conquest of the Deceangli, Ordovices and Silures tribes in the west of Britain (modern Wales). Isca is quickly converted into a bustling British civilian settlement known as Isca Dumnoniorum, complete with all the usual monumental Roman public buildings, baths (already built) and forum (construction of the latter is begun straight away, in AD 75).

Dumnonia in Maps - Map 1 c.10 BC
The first specific mention of the Dumnonii in history is in AD 43-44, during the Roman conquest of the south and east of Britain, with their initial territory shown by this map (click or tap on map to view full sized)

Some evidence of Roman military occupation remains in the territory of the Cornovii (Cornwall) and on Dartmoor (immediately west of Isca), thought to be protecting supply routes for important resources such as tin.


Roman occupation of the Cornovii site of St Austell is finally ended, for reasons unknown, making it possibly one of the last sites in the peninsula to experience Roman settlement of any kind. It is interesting to note that traditional claims of a re-emerging Dumnonii tribal aristocracy can be dated to a point not long after this, raising the possibility that it gains power to fill a vacuum or is set up in power in much the same way as princes in Wales would be by Magnus Maximus (according to tradition) in the late fourth century. Tribal Dumnonia is reborn.

251 - 253

In this period, a Roman milestone is laid, or at least inscribed, in the region of the Cornovii. It bears the names of emperors Trebonianus Gallus and Volusianus, a father and son who are proclaimed by their troops in Moesia and who are quickly murdered by the very same troops. The milestone is located at Trethevy.

Roman inscription, Trethevy
The inscribed granite milestone at Trethevy in Cornwall is now covered in lichen, but beneath this it reads 'C DOMI N GALLO ET VOLUS' ('For the Emperor Caesars our Lords Gallus and Volusian') - emperors Trevonianus Gallus and Antoninanus Volusianus reigned briefly between AD 251-253


In their occupation of Britain, the Romans may have a signalling station at Plymouth, or at least one which is manned by Roman auxiliaries or allies (the Dumnonii). Provisions would come direct from Isca and the station may also provide a staging area for tentative Roman exploration into Cornwall. No Roman coins have been found in the area but an 1894 find of a thousand coins at Compton Giffard in Plymouth shows that coin is making its way down here. None of the coins are dated later than AD 280, though.

A similar hoard has been found at Marazion near Penzance in deepest Cornwall, as well as smaller finds being made at Whitleigh and by the River Plym. Given the latest date of the coins, could any remaining Roman interest or presence here now be withdrawn? The kingdom which would appear to assume control by the start of the fourth century would (traditionally at least) appear to be entirely Dumnonian.

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