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Celtic Kingdoms of the British Isles

Celts of Britain


Regninses / Regni (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.

MapThe Regninses were a little-known tribe which 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 this 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 which 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 continental Europe.

The tribe had a form of society which 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 which was set up in AD 43 under Tiberius Claudius Cogidubnus. If that is the case then 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 at which 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.

Ancient Britons

(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).

Roman baths at Noviomagus
The Roman baths at Noviomagus in Regninses territory were uncovered by archaeologists in the 1970s and were later exposed more permanently to be incorporated into a permanent underground exhibition

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.

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.

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)

c.30 - 20 BC

It is possible that during a period of joint rule, Tincommius of the Atrebates governs the southern half of 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' own recent 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 soon-to-be Roman 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. He 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 farther west, into the territories of the Belgae and Durotriges.

43 - 80?

Tiberius Claudius Cogidubnus

Roman client king of the Atrebates, Belgae, & Regninses.


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.

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 of the Regninses?

It lies alongside a deep water harbour (now several hundred metres from the Chichester Channel, and about two kilometres east of Noviomagus), which 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 at 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 which rises above the marshes along this stretch of the coast and surrounding it on three sides.

Sequential Maps of Roman Britain AD 43-425
The Roman invasion of Britain began late in the season, using three divisions which swiftly conquered the south-east before more slowly penetrating the west and north to bring all of England and Wales under their control, as shown in this series of sequential maps (click or tap on map to view full sized)

The existence of a Roman road to the site well before the fort's construction suggests the existence of a port which 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 continental Europe 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.


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 European mainland and taking more troops with him. Parts of the fort still stand today.

Roman silver ingots
Silver ingots from the late fourth or early fifth century which were used to pay soldiers and civil servants in the Late Empire, and which were discovered at the site of the Tower of London, and at Reculver and Richborough in Kent

5th century

FeatureRoman authority has long been fading in Britain (see feature link), albeit more extensively in the west and north than along the south coast. Still, with Roman administration being expelled in 410 and some form of native government seeming to replace it, the Regninses appear to regain some level of self-control in the form of the postulated territory of Rhegin.

Rhegin (Romano-Britons)

FeatureWith the expulsion of Roman officials in AD 409 (see feature link), Britain again became independent of Rome and was not re-occupied. The fragmentation which had begun to emerge towards the end of the fourth century now appears to have accelerated, with minor princes, newly declared kings, and Roman-style magistrates all vying for power and influence while also facing the threat of extinction at the hands of the various barbarian tribes which were encroaching from all sides.

FeatureThe post-Roman territory of Rhegin seems to have emerged in the middle of the first half of the fifth century (see feature link). Occupying the south coast of Britain, to the east of the Isle of Wight (territory which today is largely incorporated within the two counties of East Sussex and West Sussex), 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 severed, the city of Noviomagus (Chichester in West Sussex) could have survived as a possible capital of the territory. Fighting from here, Britons on the south coast were probably the last native defenders of the southern Litus Saxonicum (the Saxon Shore).

While the name Rhegin is used here to denote this territory, its actual name is unrecorded. Rhegin is a viable Romano-British variation of the former tribal 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 English 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 prior to 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.

Roman Canterbury

(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, from The Oxford History of England: Roman Britain, Peter Salway, from A History of the English Church and People, The Venerable Bede (Leo Sherley-Price translation - revised by R E Latham), from The Anglo-Saxon Chronicles, Anne Savage (translator and collator, Guild Publishing, 1983), 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 being led by Vortigern from about this time). Rhegin defends the southern portion of Britain's Saxon Shore, with key posts at Noviomagus and Anderita (Roman Anderitum).

Map of Britain AD 450-600
This map of Britain concentrates on British territories and kingdoms which were established during the fourth and fifth centuries AD, as the Saxons and Angles began their settlement of the east coast (click or tap on map to view full sized)

c.450 - 455

The soon-to-be Meonware settlers 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 a revolt by the area's Jutish mercenaries. Two important battles are fought, at Aegelesthrep in 455 and Crecganford in 457. The new kingdom of Kent which 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 farther into Rhegin, perhaps satisfied for the moment with their coastal settlement area in a region which is still otherwise largely free of any Germanic settlement.

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 which is 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 or his immediate successor be defending Hampshire from Caer Gloui and Amesbury with a much stronger force which is capable of annihilating Ælle's still small force?

Aelle of the South Saxons
The coming of Ælle and his apparently pre-established status as bretwalda spelled eventual defeat and death for the Britons of modern Sussex, and quite possibly led to the siege of Mons Badonicus


FeatureThe British fort of Anderita is attacked (Roman Anderitum or Anderidos, Saxon Andredesceaster, modern Pevensey in East Sussex - which Nennius later calls Caer Ponsavelcoit - see feature link).

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 siege of Mons Badonicus, in which Ælle, as Bretwalda, attacks the Britons in the region of Caer Baddan (see feature link). 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 a century and-a-half. Rhegin quite possibly reasserts its independence, although an event in AD 501 which is recorded in the annals of the West Seaxe could signal its final end.

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


FeatureA newly arrived Saxon chieftain and his two ships of followers kill a Briton of very high rank at Portesmutha (British Portus Adurni, modern Portchester near Portsmouth - see feature link) 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 (the latter a probable British name).

Excavations at Portchester (probably known as Caer Peris by the Romano-British) by Barry Cunliffe later reveals the presence of what seems to be a sort of 'peasant militia' which is accompanied by wives and children. This ad hoc British defensive organisation may continue to operate deep into the fifth century (possibly to be crushed by Ælle in 477?).

c.514 - c.550

Following the Roman withdrawal and the occupation of swathes of the coastline, 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).

Portchester Castle
The Roman walls of Portchester Castle (British Caer Peris) would still have been standing when this former Saxon Shore fort was captured by a Saxon chieftain in AD 501, possibly ending the independence of the territory of Rhegin (click or tap on image to read more about this castle)

c.514 - c.600

Is the Suth Seaxe kingdom surrendered 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 is now very isolated and perhaps even intermingles with the Britons.


Rhegin'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 to fall to the south of London and east of Dorset. It seems likely that any remaining British population in Rhegin blends in with the remaining Suth Seaxe (Caer Gwinntguic provides a template for this sort of mutual integration and support), and forms part of the subsequent reformed South Saxon kingdom.

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