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Celtic Kingdoms of the British Isles

Celts of Britain


MapRegninses / Regni (Britons)

MapThis was a little-known British Celtic tribe that occupied modern East Sussex, south-west Kent, eastern Surrey, and the eastern edges of Hampshire. Their tribal centre was at Noviomagus (Chichester in West Sussex), close to Trisantona Fluvius (the River Arun) which joined the English Channel at Littlehampton, a little way to the east of Noviomagus. The tribe was bordered to the west by the Belgae, to the north by the Atrebates, and to the east by the Cantii, while much of their northern border was filled by the vast and near-impenetrable Weald Forest. Nevertheless, they were thinly scattered on either side of the Weald, and there were safe paths through the forest. (See the map of most of Europe's tribes around the first centuries BC and AD to view the tribe's location in relation to all other Celts.)

For the most part, the Regninses (Regnenses or Regini) appear to have been vassals of the Atrebates. They may have been a division of the Belgic Atrebates themselves, or may have been part of a confederation of smaller tribes that predated the arrival of the Atrebates throughout Sussex and Hampshire. They seem to have escaped true conquest by the Atrebates and even any real influence from them, but their obvious links with them are shown by Noviomagus being the earliest capital of the Atrebates, especially as it lies close to an easy-accessible coastline for migrating Celts travelling over from the Continent.

The tribe had a form of society that made a greater use of hill forts than its neighbours to the west. Its location along the southern shore of Britain would have made it one of the more civilised Celtic tribes. Its people probably handled a great deal of trade with the tribes in Europe right up until the Romans conquered Gaul, and along with the Atrebates could have seen the conquest as an opportunity to increase their regular trade in fine cloth, hunting dogs and military items. The process worked both ways, enabling them to absorb new ideas, giving them advantages in culture and technology which some of their neighbours did not possess.

Their name, 'Regninses', means 'people of the kingdom'. The name was recorded by the Romans but its origin is unknown. There are at least two possible sources for it, the first and most obvious of which is that the people were merely the subjects of the Roman client kingdom set up in AD 43 under Tiberius Claudius Cogidubnus, in which case the name is not Iron Age Celtic at all, but a Roman invention (or at least one which was permitted by the Romans). The other possibility is that it was some kind of collective name for the people of the Weald, perhaps coined at a time when the Atrebates were beginning to exert their control over the region and the Regninses either needed to assert or establish their own identity, or the Atrebates enforced one upon them.

(Information by Peter Kessler, with additional information by Edward Dawson, from Geography, Ptolemy, from The Oxford History of England: Roman Britain, Peter Salway, from The Oxford History of England: Roman Britain, Peter Salway, from The La Tene Celtic Belgae Tribes in England: Y-Chromosome Haplogroup R-U152 - Hypothesis C, David K Faux, from Atlas of British History, G S P Freeman-Grenville (Rex Collins, London, 1979), and from External Link: Proto-Celtic Word List (PDF).)

c.100 - 80? BC

The date at which the Belgic Atrebates arrive in Britain is unknown, but it may be around this period. They possibly migrate into the country from the south coast (most likely via Selsey in West Sussex, precisely the same point at which the later South Saxons also land), and found an early tribal capital at Noviomagus (modern Chichester in West Sussex). Over time they migrate north-westwards, integrating with earlier Celtic populations in the region and founding a new settlement at Calleva, although this remains relatively minor until the late first century BC.

However, coin distribution contradicts this picture, suggesting that the Atrebates arrive via the Thames, settling in the Upper Thames Valley and migrating southwards from there. This would make much stronger the possibility that the Regninses are an earlier Celtic population who are later subjugated by the Atrebates.

Roman baths at Noviomagus
The Roman baths at Noviomagus were uncovered in the seventies and are now being exposed again to be incorporated in a permanent, underground, exhibition

c.90 - 60 BC

Gallo-Belgic C coins can be found which are tentatively identified with Diviciacus of the Suessiones. Finds are concentrated amongst the Cantii, but can be found as far west as the Sussex coast, in the territory of the Regninses, and up to the Catuvellauni territory around the Wash. During this late Iron Age period, it seems that the Regninses capital is located at a prehistoric settlement at Selsey (in West Sussex), possibly around the Mixon rocks to the south of Selsey itself. Archaeological evidence to support the theory has yet to be found, but plenty of Atrebatean and early Roman coins have been found in this area. The settlement declines during the Roman period and is later covered by rising sea levels.

c.30 - 20 BC

It is possible that during a period of joint rule, Tincommius of the Atrebates governs the southern half of the Atrebatean territory from the secondary capital of Noviomagus, which is within the territory of the Regninses.

c.AD 15

Eppillus of the Atrebates is overthrown by his younger brother after the latter builds up a following of nobles who are disaffected by Eppillus' grab for power. He flees to the land of the Cantii, probably passing through Regninses territory along the way, where he overthrows the ruler and takes command.


The Romans conquer the kingdom under the command of Governor Aulus Plautius. The Regninses territory is taken from the control of the Atrebates and is reorganised into the pro-Roman kingdom of the Regninses under the rule of Tiberius Claudius Cogidubnus. He may be the son of Verica, the last native king of the Atrebates, and appears to be granted the titles 'Rex Britannorum' (king of Britain) and Legatus Augusti (imperial legate). A military supply base is built at Noviomagus from which to provision the legions as they push further west, into the territories of the Belgae and Durotriges.

43 - 80?

Tiberius Claudius Cogidubnus

Roman client king of the Regninses and Belgae.


Direct rule under the Romans follows the apparently peaceful death of Cogidubnus (which remains unrecorded and therefore, probably, unspectacular or noteworthy). During the last years of his life, a palatial Romano-British villa is built at Fishbourne, one of the largest ever seen in Britain, and is quite possibly his seat of power. It lies alongside a deep water harbour (now several hundred metres from the Chichester Channel) about two kilometres east of Noviomagus that is probably built as early as AD 43 or 44 as part of the Roman supply chain.

The former tribal territory of the Atrebates is subsequently organised into the civitates (administrative districts within a Roman province) of the Atrebates, Regninses, and possibly the Belgae. The Regninses are governed from the tribal capital Noviomagus Regnorum.


Writing around this time, the geographer, Ptolemy, notes that the 'Regni'  are situated below the Atrebates and Cantii with their chief town of Noviomagus. In this century the town gains a bank and timber palisade which is later replaced with stone, probably in the third century.


The Saxon Shore fort of Anderitum or Anderidos (the modern Pevensey Castle) is constructed on ground not previously used for any form of habitation. The ground is a peninsula that rises above the marshes along this stretch of the coast and surrounding it on three sides. The existence of a Roman road to the site well before the fort's construction suggests the existence of a port that has yet to be found by archaeologists. The fort appears to be built not to prevent incursions by marauding Saxons but to provide defensive capabilities during a period in which Britain is isolated from the Continent by the rebellion of Marcus Mausaeus Carausius, who declares himself to be Roman emperor (a later date of the 330s or 340s is sometimes also given to the fort's founding).

Perhaps it is no coincidence that the extensive villa at Fishbourne is apparently destroyed by fire in the same period (late third century). Archaeology has shown that lead from the melting roof falls onto the mosaic beneath it. The villa is subsequently abandoned. Many of its precision-made building stones are re-used in other constructions and a number of late Romano-British burials subsequently take place at the site.

Fishbourne villa
Fishbourne villa was one of the most extensive and richly-decorated establishments in the whole of Britain, surely a palace fit for a (client) king?


The fort of Anderitum undergoes repair work under the direction of Roman General Stilicho. He is known to be in Britain in 398 where he is suspected to have defended the provinces during the second of the 'Pictish wars'. He certainly attends to the island's defences before leaving for the Continent and taking more troops with him. Parts of the fort still stand today.

5th century

By this time the Romano-British Regninses appear to have regained some level of self-control in the form of the postulated territory of Rhegin.


FeatureThis post-Roman territory seems to have emerged in the middle of the first half of the fifth century. According to the scanty evidence available, it was just one of a host of territories that began to appear in this period as the central British authority struggled hold the country together between AD 410-425. Occupying the south coast to the east of the Isle of Wight (territory which today is largely incorporated within the two counties of Sussex, east and west), the Rhegin Britons were neighboured to the east by Ceint, to the north-west by Caer Celemion, and to the west by Caer Gwinntguic.

After ties with Rome were formally severed in AD 410, the city of Noviomagus (Chichester in West Sussex) could have survived as a possible capital of the territory. Fighting from here, the Britons on the south coast were probably the last native defenders of the Litus Saxonicum (the Saxon Shore). While the name Rhegin is used here its actual name is unrecorded, but Rhegin is a viable Romano-British variation of the tribe's former name of Regninses. Its use is supported by a somewhat poorly-accepted opinion which suggests that the Rhegin Britons were also involved in the colonisation process of Armorica across the Channel. They would have taken territory in the east of early Domnonia, and their colony was seemingly soon taken over by Vannetais itself, but it later emerged into recorded history as the county of Rennes.

Archaeological evidence points to the Rhegin region of the south coast being a likely base for friendly mercenaries before Ælle's invasion of AD 477. Two cemeteries in West Sussex, at Apple Down and at Highdown (near Worthing), show evidence of use by Saxon foederati, suggesting that the widespread use of Saxon mercenaries during the early fifth century also includes at least two bases in Rhegin, in the area between the Ouse and Cuckmere.

(Information by Peter Kessler, with additional information by Edward Dawson, from English Historical Documents c.500-1042: Chronicle of Nantes (Chapter 27), Dorothy Whitelock (Ed, Second Edition, 1979), from The Oxford History of England: The English Settlements, J N L Meyers, from The Oxford History of England: Anglo-Saxon England, Sir Frank Stenton, and from External Link: Pevensey Castle.)


It seems possible that Rhegin emerges around this point as a recognisable territory in its own right, at the same time as Ceint emerges to the east. It is probably governed by a magistrate in the Roman style who acts under the authority of the country's central authority (traditionally formed by High King Vortigern). Rhegin defends the southern portion of the Saxon Shore, with key posts at Noviomagus and Anderita (Roman Anderitum).

c.450 - 455

The Meonware sail around Southampton Water and along the Solent to settle in eastern Hampshire, possibly on the very edges of Rhegin. These Jutes are extremely obscure during their brief independent existence, but they certainly exist in this location within a decade of this date. It is possible that they initially serve as laeti, and may not be seen by the British of Caer Gwinntguic and Rhegin as a threat. The founding of the Anglo-Saxon cemetery at Highdown has been dated to about 450, supporting the idea of an influx of mercenaries at this time.

455 - 457

The British kingdom of Ceint is overrun at the start of the revolt of Jutish mercenaries. Two important battles are fought, at Aegelesthrep in 455 and Crecganford in 457. The new kingdom of Kent that is formed by the Jutes appears to incorporate the traditional territories of the Cantii, including all of Kent, East Sussex bordering Rhegin, eastern Surrey and London south of the Thames. However, the Jutes appear not to venture further into Rhegin, perhaps satisfied for the moment with their conquests.

Map of Rhegin
This map of Rhegin for about AD 477 shows the principle British settlements along the Sussex coast immediately prior to the brutal Suth Saxon invasion of that year


Newly arrived Saxons under Ælle land at Selsey on the south coast (modern West Sussex) and beat off the Britons of Rhegin who oppose their landing, driving them to take refuge in the great forest the Saxons call Andredesleag (The Weald). Suddenly, the southern Saxon Shore has been breached in a far more major way than the arrival of the Meonware had threatened, and Caer Gwinntguic is cut off from the south coast.


The Suth Seaxe defeat the Britons at the place the Saxons call Mearcraedes burna (modern location unknown). The name of the location has been plausibly interpreted to mean 'the stream of the agreed frontier'. It may therefore relate to a boundary based on one of the river valleys which divide the Sussex coastal plain and its hinterland into naturally self-contained sections. There is no means of knowing which valley bears this name, but it seems to suggest a temporary frontier between Briton and Saxon.

It is interesting to note that the Suth Seaxe turn eastwards, along the line of the Weald, rather than westwards into the fertile open plains of Hampshire. It suggests that this section of the Saxon Shore is comparably easy to pick off (although it still takes Ælle fourteen years to achieve this). Could Ambrosius Aurelianus be defending Hampshire from Caer Gloui and Amesbury with a much stronger force that is capable of annihilating Ælle's still small force?


The British fort of Anderita is attacked (Roman Anderitum or Anderidos, Saxon Andredesceaster, modern Pevensey in East Sussex - which Nennius later calls Caer Ponsavelcoit). The fort is conquered by Ælle and Cissa and its entire garrison is slaughtered by the Suth Seaxe in what must be a desperate fight. This seems to end any British opposition in the region (the site is not reoccupied until 1042, when Harold Godwinsson, earl of Wessex, refortifies the position).

Noviomagus is left highly vulnerable by this loss. It seems that it is partially destroyed during the completion of Ælle's conquest of the area, and probably falls to the Suth Seaxe, or at least becomes tributary to them. An isolated client kingdom or vassal state may also remain in East Sussex, wedged in by Suth Seaxe, Cantware and the forest.


FeatureThis is the probable date of the battle of Mons Badonicus, in which Ælle, as Bretwalda, attacks the Britons in the region of Caer Baddan. His force is defeated by the Britons. The Suth Seaxe must suffer heavy casualties as they are so weakened that they now drift into obscurity for around 150 years. Rhegin quite possibly reasserts its independence, although an event in 501 recorded in the annals of the West Seaxe could signal its final end.


A newly arrived Saxon chieftain and his two ships of followers kill a Briton of very high rank at Portesmutha (British Portus Adurni, modern Portsmouth) This could be one of the last surviving parts of Rhegin. Alternatively, the Briton could be Gereint of Dumnonia). The name of the Saxon chieftain appears to have been lost, as it has been conveniently recorded as Port in the West Seaxe annals. His sons are Bieda and Mægla (a probable British name).

Excavations at Portchester (probably known as Caer Peris by the Romano-British), conducted by Barry Cunliffe, have revealed the presence of what seems to have been a sort of 'peasant militia' accompanied by wives and children; this ad hoc British defensive organisation may have continued far into the fifth century.

Pevensey Castle (Anderita)
The British fort of Anderita was originally built by the Romans as part of their Late Empire Saxon Shore fortifications, and the main structure still survives as Pevensey Castle

c.514 - c.550

Following the Roman withdrawal, Noviomagus has declined but has remained occupied. Now the rebuilding of the town is begun by the king of the Suth Seaxe, Cissa, although its old name is forgotten in favour of that of its new ruler, becoming Cisseceaster (Cissa's fort, modern Chichester).

c.514 - c.600

Is the Suth Seaxe kingdom lost to the Britons? The invaders lose their prominence and are not mentioned in any records until the middle of the seventh century. Following Badon, strong Jutish influences from Kent enter the land, suggesting an extension of Kentish rule over the eastern parts of the territory. If there still exists a British enclave in East Sussex, it is probably now freed to move westwards and reoccupy areas of West Sussex. Whatever remains of the Suth Seaxe remains very isolated and perhaps even intermingles with the Britons.


MapRhegin's western neighbour, Caer Gwinntguic, falls to the West Seaxe, making the territory very vulnerable on that border. If there are still independent Britons in Rhegin by this date, they must lose their independence within the next fifty years or so, following the destruction of Caer Celemion. This latter city is the last British-held territory south of London and east of Dorset to fall. It seems likely that any remaining British population in Rhegin intermingles with the remaining Suth Seaxe and forms part of the subsequent reformed South Saxon kingdom.