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Celtic Kingdoms of the British Isles

Celts of Cymru



FeatureFounded in circa AD 424, this small coastal kingdom was centred on the Bay of Cardigan. According to tradition, Ceredigion was originally part of the territory governed by the Gododdin chief, Cunedda, after he was invited by Magnus Maximus to settle in north-west Wales. Cunedda granted the land to Ceretic as his own kingdom, and it was named after him. The earliest form of that name may have been Ceretica. Ceredigion means 'the people/followers of Ceretic'.

Situated along the western coast of Wales, its territory corresponded roughly to that of the modern county of Ceredigion which includes the towns of Aberaeron, Aberystwyth, Cardigan, Lampeter, Llanddewi brefi, New Quay, and Tregaron, and it is where the rivers Severn and Wye have their sources. The Cambrian Mountains covered much of the east of the kingdom and its hilly geography made it difficult for foreign invaders to conquer. As a coastal kingdom, its creation was a good strategic move as it sealed the vulnerable coastal gap between Dyfed to the south and Gwynedd to the north, thereby preventing any further Irish gains in Wales. For part of its length the River Teifi formed the border between Ceredigion and Dyfed.

(Additional information by Edward Dawson, and from The Landscape of King Arthur, Geoffrey Ashe.)

c.424 - c.453

Ceretic / Corotic / Ceredig

Fifth son of Cunedda Wledig.

The name Ceretic or its various versions means 'beloved of Dagda', Dagda being Dag, the solar god who is cognate with English 'day', plus 'da', meaning 'good' - 'good Dag', in the same way that Christians might say 'blessed lord'. The same format is used in the name Carantoc, and in an earlier form with Togodumnus of the Catuvellauni.

Corun ap Ceredig

Son. Apparently predeceased his father.

In Ceretic's later years, when the kingdom is under threat of attack by Irish raiders, he is advised to abdicate in favour of his young grandson, Carantocus, but the saintly Carantocus is horrified at such a prospect and flees the court to live as a hermit at Edilu. Becoming the learned St Carannog/Carantoc (after whom is named Crantock in Cornwall), he is mentioned in connection with Arthur and a certain Cado who is probably Cado, king of Dumnonia in the early sixth century.

Carantocus / St Carannog ap Corun

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

c.453 - c.490

Usai ap Ceredig

Son of Ceretic.

c.490 - c.525

Serwyl ap Usai

c.525 - c.560

Boddw ap Serwyl

c.560 - c.595

Arthfoddw ap Boddw

c.595 - c.630

Arthlwys ap Arthwfoddw

c.630 - c.665

Clydog ap Arthlwys

c.665 - c.700

Seisyll ap Clydog

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.


Map Seisyllwg (with Ystrad Tywy)

Seisyllwg consisted of the former kingdom of Ceredigion together with the newly conquered territory of Ystrad Towy. 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.

(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).)

c.700 - c.735

Arthwyr ap Seisyll

c.735 - c.770

Dyfnwal ap Arthwyr

c.770 - c.807

Meurig ap Dyfnwal / Morydd

by 800

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



(Annales Cambriae).

c.808 - 872

Gwgan ap Meurig

Son of Meurig. Drowned and left no heir.


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.