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Celtic Kingdoms of the British Isles

Celts of Britain


Demetae (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.

MapBy the early years of the first century AD, this tribe occupied south-western Wales. This area later formed the kingdoms of Dyfed and Ceredigion, while today it covers the county of Pembrokeshire, the western half of Carmarthenshire, and perhaps the lower two-thirds of Ceredigion (all of which were contained within the preserved county of Dyfed until the 1996 reorganisation). The tribe was bordered to the north by the Ordovices, and to the east by the Silures, while to the west lay Ireland and the ever-present threat of raiders. To the south, across the Bristol Channel, were the Dumnonii and Cornovii (see the map of most of Europe's tribes around the first centuries BC and AD to view this tribe's location in relation to all other Celts).

The tribal boundaries for the pre-Roman period in Wales are generally more uncertain than in England. Rome had no political contact with the westernmost tribes prior to the invasion of AD 43, and even then it took another generation before any serious attempt was made to conquer those tribes which were in the far west (those tribal Britons in the west were often considerably more rugged and dogged in their resistance to the invasion). A date for the arrival of the Demetae in the region cannot be pinpointed with any accuracy, but they were probably part of the first or second wave of Celtic immigrants into Britain, arriving from around 750 BC onwards and perhaps reaching the west coast in the fourth century BC.

It is claimed that the tribe's name was derived from their warrior god, Demetos, whom it seems someone decided had to be a god of drunkenness. However, this seems dubious for an otherwise unattested god, unless it is one which is noted in Latin on a Pictish inscription as Mars Medocio (or Maedoc). The second part of Medocio is 'doc', seen often in Welsh names, which is most likely a Brythonic form of the god, Dagda. The mistake made is in where to break the word, with 'med-ocio' giving 'mead', and 'me-docio' giving some variant of Dagda. In Gaulish and Latin the prefix 'de-' means 'from' or 'derived from'. This would be formed in the same manner as the 'de-ceangli', from the Gangani, and the de-cantae from the Cantiaci. So 'de-metos' is more likely to be 'from the god Dadga'.

An alternative is that the Demetae were an offshoot of an earlier tribe whose name is not recorded because they did not survive into the era of Roman expansion. The root 'met' ('de-met-os') appears as a name in Irish Gaelic as 'Ailill mac Máta', so 'Mata' is a perfectly suitable equivalent. That being so, it could be conjectured that Mata was a leader's name, and then a splinter group formed 'from' the older tribe, giving us 'de-mata'. Demetae is generally pronounced de-meet-ay, with the emphasis on the middle syllable.

Ptolemy mentions the Leuca Fluvius (River Loughor, Afon Llwchwr) in connection with the tribe, which divides Llanelli from Swansea and may have formed the tribe's eastern border. There were plenty of hill forts in the tribe's land, which showed an affinity with those found in south-western England. This suggests a level of contact with those people, the Dumnonii, and perhaps a shared heritage from the time at which they were located further east in the country. In all likelihood, these arrivals intermingled with earlier Celto-Ligurian peoples in the region, or possibly with migrants from Ireland. Most of their ordinary folk lived in fortified farmsteads, just as with the Ordovices.

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 the Ravenna Cosmography (compiled by an anonymous cleric), from Geography, Ptolemy, and from The Expulsion of the Deisi available as a PDF via External Link: The Four Branches of the Mabinogi.)

c.350 BC

It is estimated that the second wave of Celtic migrants settles in western Britain (modern Wales) around this time, replacing or absorbing the previous Celto-Ligurian peoples of the Bronze Age and perhaps also (or instead) mingling with immigrants from Ireland. These second wave settlers probably include the early Demetae. Affinities in hill fort construction with the Dumnonii suggests either trading links across the Bristol Channel or a shared heritage.

Castle Dore
The remains of the Castle Dore hill fort, constructed by the inhabitants of Cornwall in this period, with them possibly sharing a heritage with the recently-arrived Demetae settlers of western Wales

AD 49

Caratacus, former ruler of the Catuvellauni and still apparently recognised as the dominant battle leader amongst the Britons, moves his base of operations from the territory of the Silures to lead a general coalition against Roman Governor Ostorius from the territory of the Ordovices.

The Demetae appear to play little or no part in his popular resistance against the invaders, and even Tacitus, writing around AD 98, does not mention them in connection with the Roman invasion. Instead, they remain behind their probable northerly border which the Romans later name Stuctia Fluvius (the Afon Ystwyth), which empties into the Irish Sea at Aberystwyth.


The Romans appear to subdue this area of Wales relatively easily with the defeat of British battle leader Caratacus in this year. The Demetae seem to be relatively comfortable with their client status.

FeatureThe Romans also take over their gold mining activities, at sites such as Dolaucothi (which the Romans name Luentinum and which is now in Carmarthenshire, near Pumsaint). These mines are already as much as a thousand years old, predating the arrival of the Demetae in the region (see feature link).

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)


The Kingsholm fortress in the territory of the Dobunni is prone to flooding so a new and larger fortress is built on the higher ground one kilometre to the south, at what becomes Gloucester Cross. It is around this fort that a civilian settlement grows up, forming the early city. Troops are based here in the build-up to the invasion of western Britain (modern Wales), with the first strike being planned against the Silures and Demetae. However, this is apparently delayed by the events of AD 69, the 'Year of Four Emperors'.

70 - 74

FeatureAs a prelude to campaigns further north and east, the Romans stamp their authority on the region with the building of roads and forts. One of these is located on what is probably the eastern frontier, at Leuca Fluvius (the River Loughor), perhaps to protect both Romans and Demetae from attacks by the more aggressive Silures on the other side of the river. The fort is named Leucarum (Loughor, now in West Glamorgan - see feature link).

Moridunum Demetarum
The Roman tribal capital at Moridunum Demetarum was founded soon after AD 74, abandoned or destroyed shortly before or after AD 200, and later reoccupied until the end of the Roman period in Britain

The tribe is granted civitas status, with a capital at Moridunum Demetarum (British Caerfyrddin, or modern Carmarthen). This is the only major settlement in the territory, formed outside the walls of the fort at Carmarthen which itself is founded about this time. The tribal capital receives little mention after this point, although Ptolemy notes its location and the route to it. The Ravenna Cosmography of about AD 700 calls it Macatonion. Elsewhere in the region, the former Iron Age mines at Dolaucothi are reworked by the Romans.


In his description of the Ordovices to the north-east of Demetae territory, Ptolemy mentions the Stuctia Fluvius (the modern Afon Ystwyth), which possibly forms the border between the two tribes.

c.193 - 217

The Roman fort at Moridunum Demetarum appears to be abandoned or destroyed during the Severan period. Archaeological evidence shows a probable gap in occupation, which is especially visible in the lack of pottery. The site is later reoccupied.

Romano-Britons burying treasure
With discord building in the country (and reaching a peak between about 420-450), many Romano-Britons began leaving in a hurry, burying their wealth in the hope that they could return in better times to collect it


Roman authority fades much more quickly in the west than in areas which today form England. Unlike the rich areas in the east, the west has always been under military control, and this control has suffered in the fourth century as troop numbers continue to fall.

In this year, the former Demetae territory is part of a rearrangement of the western defensive structure. The apparent commander in Britain, Magnus Maximus, entrusts command of the region to one of his sons, but following the death of Maximus the region seems quickly to evolve into a kingdom named Demetia, showing that Demetae tribal identity is still alive and strong.

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