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Celtic Kingdoms of the British Isles

Celts of Cymru


Ceredigion (Romano-Britons) (Wales)

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.

FeatureIn the west, largely in what would become modern Wales, this process seems to have started earlier and taken place more quickly. Even by the start of the fifth century it is apparent that several territories had emerged here. The process seems to have been triggered by the reorganisations of Magnus Maximus in the late fourth century (see feature link), with what later tradition would claim as the creation of the 'kingdoms' of 'North Wales', 'South Wales', and 'Mid-South Wales'.

FeatureOf those, it seems to have been North Wales which gained the bulk of the responsibility, and territory. What would become Ceredigion (see feature link) abutted the territory of Venedotia to its north, Demetia to the south, and Paganes to the east, plugging the gap in coastal defences between them. Western Britain's coastline was fully protected from Irish raiders, at least in theory, while Cunedda turned Venedotia into an early principality of what was fast becoming medieval Wales.

FeatureFounded circa AD 424, the small coastal kingdom of Ceredigion was centred on Cardigan Bay, in territory which would likely have belonged in pre-Roman Prydein to the Demetae to the south and Ordovices to the north. According to tradition (and Nennius - see feature link), Cunedda granted the land to his fifth son, Ceretic, as his own principality, and it was named after him. The earliest form of his name may have been Ceretica, while 'Ceredigion' means 'the people/followers of Ceretic'. Unfortunately little detail exists in regard to his immediate descendents outside of a Welsh pedigree.

The principality's territory corresponded roughly to that of the modern county of Ceredigion, which includes the towns of Aberaeron, Aberystwyth, Cardigan, Lampeter, Llanddewi Brefi (actually a village), New Quay, and Tregaron. It is also where the rivers Severn and Wye have their sources.

The Cambrian Mountains covered much of the east of the principality, and its hilly geography made it difficult for foreign invaders to conquer. Even today the county of Ceredigion remains sparsely populated. For part of its length the River Teifi formed the border between Ceredigion and Dyfed (the later form of 'Demetia'). The principality's northern border was always the River Dyfi (Welsh Afon Dyfi), although the southern border changed often, usually due to competition with Dyfed. This suggests a very stable relationship with Gwynedd in the north.

Roman Canterbury

(Information by Peter Kessler, with additional information by Edward Dawson, from The Landscape of King Arthur, Geoffrey Ashe, from The Four Branches of the Mabinogi, Will Parker, from Welsh Genealogies AD 300-1400, Peter Bartrum, from A History of Wales, John Davies, 1994, from Wales and the Britons, 350-1064, T M Charles-Edwards (Oxford University Press, 2013), from History of the Kings of Britain, Geoffrey of Monmouth, from A History of the English Church and People, The Venerable Bede (Leo Sherley-Price translation - revised by R E Latham), from Atlas of British History, G S P Freeman-Grenville (Rex Collins, London, 1979), from Etymological Glossary of Old Welsh, Alexander Falileyev, from The Oxford History of England: Anglo-Saxon England, Sir Frank Stenton, from the Historia Brittonum (The History of the Britons), Nennius, and De Excidio Brittaniae et Conquestu (On the Ruin of Britain), Gildas (both J A Giles, Ed & Trans, 1841, published as part of Six Old English Chronicles (Henry G Bohn, London, 1848)), and from External Link: Ancient Welsh Studies.)

fl c.424 - c.453

Ceretic / Corotic / Ceredig

Fifth son of Cunedda Wledig of Venedotia.

The name 'Ceretic' or its various alternatives (such as the Latin adjective, 'Cereticianus', or the name Cereticus) mean 'beloved of Dagda', Dagda being Dag, the solar god who is cognate with the English 'day', plus '-da', meaning 'good', resulting in 'good Dag', in the same way that Christians might say 'blessed lord'.

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)

The same format is used in the name Carantoc (see below), and in an earlier form with Togodumnus of the Catuvellauni. Ceretic, according to tradition, marries Meleri, one of the many daughters of Brychen Brycheiniog, founder of the principality of Brycheiniog.

fl c.440s?

Corun ap Ceredig

Son. Apparently predeceased his father.

In Ceretic's later years, when the principality is under threat of attack by Irish raiders (one group manages to seize control of the Paganes around AD 441), he is advised to abdicate in favour of his young grandson, Carantocus. However, the saintly Carantocus is horrified at such a prospect so he flees the court to live as a hermit at Edilu.

FeatureBecoming the learned St Carannog or Carantoc (after whom is named Crantock in Cornwall - see feature link for its churches and chapels), he is mentioned in connection with Arthur and a certain Cado who is probably Cado, ruler of Dumnonia in the early sixth century.

Brecon Beacons
The fluctuating fortunes of the principality of Brycheiniog took place in the dramatic landscape of the Brecon Beacons in south-eastern Wales

fl c.440s?

Carantocus / St Carannog ap Corun

Son. Fled the court to become St Carannog / Carantoc.


Following the death of Cunedda, his son Einion Yrth succeeds as princeps or magistrate of Venedotia. The principality remains politically whole under his governance, and regionally very powerful. However, the territory within it is divided between Cunedda's surviving sons, who then operate as sub-kings to Einion Yrth. Only Ceredigion appears to fall outside this overlordship.

fl c.453 - c.460

Iusay ap Ceredig

Son of Ceretic. Potentially aged.

fl c.496 - c.480

Serguil / Serwyl ap Iusay


fl c.480 - c.500

Usai ap Serwyl

Son. Invented to plug a gap in the pedigree.

fl c.500 - c.525

Serwyl ap Usai

Son. Invented to plug a gap in the pedigree.

fl c.525 - c.560

Boddgu / Boddw ap Serwyl



The death of Maelgwyn Gwynedd of Venedotia can be said to be the end point for any remaining notion of 'Roman-ness' which may have remained in the office of a ruler of any territory in the west and north of Britain (and that of magistrate in the south and east). A kingdom or principality of Gwynedd can said to be birthed by this time.

Saxon cremation urns from the area around London
By the mid-sixth century, Saxons were settling around Londinium, and using pots such as these for their cremation burials, while the seax blade is generally more Frankish than Saxon, but the city itself remained overgrown and in ruins for another half a century

fl c.560 - c.595

Artboddgu / Arthfoddw ap Boddw


fl c.595 - c.630

Artgloys / Arthlwys ap Arthwfoddw



In one of the bloodiest and hardest fought battles of its time, several British kings form a coalition to halt Æthelfrith of Bernicia at the Battle of Caer Legion (Chester). Cearl of the Mercians could also be involved on the British side (according to scholarly theory).

FeatureIago ap Beli of Gwynedd and Selyf of Powys are both killed, and the battle is a disastrous British defeat. As lords of Gwynedd, Isaag ap Einion of Dunoding, Idris Gawr of Meirionnydd, and Cadwal Cryshalog of Rhos would also be expected to involve themselves with their own bands of warriors (see one of Geoffrey of Monmouth's more accurate entries about this campaign via the feature link).

fl c.630 - c.665

Clydog ap Arthlwys



Cadwaladr of Gwynedd is probably killed by the great plague which hits the country. There is no obvious candidate to replace him, and such is the extent of the loss of territory over the past century that there is no longer a 'British' Britain over which to claim any high kingship.

Map of Gwynedd
Despite, or because of, the very fringe involvement with Rome of the Votadini British, Venedotia looked very heavily to Roman influences until well into the sixth century, with it being here that one of the last signs of the concept of Roman citizenship could be found, on a gravestone where a 'cousin' of Maelgwn Gwynedd proudly proclaimed himself a 'Venedotis Cives', a citizen of Venedotia

Instead, the rival Anglo-Saxon 'bretwaldaship' takes precedence. States such as Dyfed, Gwynedd, and Powys remain independent in the west, with Dumnonia in the south-west, and Alt Clut in the far north, but everywhere else the English are in control.

fl c.665 - c.700

Seisyllt / Seisyll ap Clydog

Son. Expanded the principality and renamed it Seisyllwg.

Seisyll embarks on a series of conquests, adding to his territory the three cantrefs of Ystrad Tywy. With his neighbour Dyfed now denuded of a great swathe of its own lands, Seisyll has formed an enlargened kingdom - a third bigger than it had been - which bears his name: Seisyllwg.

Seisyllwg / Ceredigion (with Ystrad Tywy) (Wales)

Seisyllwg consisted of the former kingdom of Ceredigion together with the newly conquered territory of Ystrad Tywy (alternatively shown as Towy or Towi). Note that the dates given for the reigns of Seisyll and his immediate descendents must be treated with caution, being little more than educated guesses. The only secure date available is for the death of Gwgan ap Meurig which is derived from the Annales Cambriae.

The entire enlargened principality of Seisyllwg may have been known as such during the lifetime of its founder, but within a generation all ten commotes were simply known as Ceredigion.

Rhuddlan Castle in Wales

(Additional information by Hywel George, and from the Annales Cambriae, James Ingram (taken from the Harleian manuscript, the earliest surviving version, London, Everyman Press, 1912).)

fl c.665 - c.700

Seisyllt / Seisyll ap Clydog

Son. Expanded Ceredigion and renamed it Seisyllwg.

fl c.700 - c.735

Arthen / Arthwyr ap Seisyll


fl c.735 - c.770

Dyfnwallon / Dyfnwal ap Arthwyr


fl c.770 - c.807

Morydd / Meurig ap Dyfnwal


by 800

The kingdoms of Builth and Gwrtheyrnion are taken directly within Seisyllwg.

fl 807?


(Annales Cambriae).

fl c.808 - 872

Gwgan ap Meurig

Son of Meurig. Drowned and left no heir.

fl c.810

Angharad ferch Meurig

Sister. m Rhodri Mawr, king of Gwynedd & Powys.

872 - 873

Gwgan is drowned while crossing the River Llychwr in Gower whilst chasing off a Viking raid. The kingdom passes to his brother-in-law, Rhodri Mawr, after he quickly marries into the bereaved family. Rhodri is now king of much of north and central Wales. From this point onwards, Seisyllwg is ruled by a branch of the kings of Gwynedd as a sub-kingdom. In 873, Rhodri's son, Cadell, is placed in command of Ceredigion and the palace at Dinefwr.

873 - 909

Cadell ap Rhodri

'King of South Wales'. Founder of the House of Dinefwr.


Upon the death of Rhodri Mawr, and according to his wishes, Wales is officially divided between his sons. Anarawd succeeds him in Deheubarth, Merfyn in Powys, and Cadell is confirmed in Seisyllwg.


Cadell ap Rhodri and his son, Hywel Dda, conquer Dyfed. Hywel is granted control of the kingdom, a position which is an entirely legitimate claim in principle (if not in law) thanks to his marriage to Elen ferch Llywarch ap Hyfaidd, effectively the heiress of Dyed.

909 - 920

Clydog ap Cadell

Son. No heir. Mentioned in the Annales Cambriae.


Drawn into full union with Dyfed under Cadell's second son, Hywel Dda, creating the kingdom of Deheubarth.

Hywel Dda of Deheubarth and Wales
Unusually for the dominant rulers in later medieval Wales, Hywel Dda was a man of the south, having been the driving force behind the creation of Deheubarth out of several smaller states and territories (1909 oil imagining the prince's appearance)


The death of Hywel Dda, king of all Wales, leaves the country divided. Hywel's sons, Owain, Rhun, Rhodri and Edwyn, take possession of his estates in South Wales, with Rhodi becoming king of Deheubarth itself and Owain becoming prince of Ceredigion.

950 - 957

Owain ap Hywel Dda

Prince of Ceredigion.

952 - 953

As part of the ongoing conflict between Deheubarth and Gwynedd, Owain leads an army into the North Wales kingdom and engages its men at the Battle of Aberconwy. The fighting is so fierce that both sides are forced to withdraw, having sustained heavy losses. The following year, Gwynedd repays the compliment, invading and devastating Ceredigion and being driven out by more fierce fighting.


Owain succeeds to the throne of Deheubarth and Ceredigion is fully reunited with it under him as its single ruler.

by 1100

Ceredigion is now regarded as a duchy of Gwynedd, and is ruled in the king's name by his sons.

? - 1143


Ruled the North. Brother of Owain Gwynedd.

before 1143 - ?

Hywel ap Owain Gwynedd

Ruled the South. Son of Owain Gwynedd. Gained North in 1143.


The county of Ceredigion is established by Edward I following the completion of his conquest of Wales. Today's county of Ceredigion has largely the same borders as the late medieval county of Cardiganshire.

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