History Files

Celtic Kingdoms of the British Isles

Celts of Cymru


MapBuilth (Buellt)

This tiny post-Roman kingdom was located in central Wales, with the Cambrian Mountains and the region of Gwrtheyrnion to the north, Powys and the River Wye to the east, Brycheiniog and the Mynydd Epynt range to the south, and Ceredigion to the west. It seems to have emerged out of Roman occupation as part of Vortigern's ancestral lands in the Pagenses region (early Powys and Pengwern). He handed out parcels of territory to his sons upon his own accession as high king of Britain, with Vortimer gaining Gwerthefyriwg (Gwent), Cadeyrn Fendigaid gaining the Pagenses territory, and  Pascent gaining Buellt and Gwrtheyrnion. Apparently Pascent's claim was confirmed by Ambrosius Aurelianus at Caer Gloui after Vortigern's death.

The kingdom of Buellt (in its earliest years, before the Brythonic language evolved over a very short space of time into early Welsh) was centred on Caer Bedris (or Beris) in Builth (the later Welsh version of the name), in modern Powys. The modern town lays across the River Wye, on what was an important north-south route which forded the river here. The town itself is largely a Norman creation, seemingly as a bastide, a form of medieval market settlement. The shape of the parish church grounds suggest a possible connection to the earlier British Church.

As mentioned, the sub-kingdom or region of Gwrtheyrnion was part of Buellt's territory. The Buellt kings often seem also to be referred to as kings of Guorthegirnaim (Gwrtheyrnion) as if this were somehow a more important territory than Builth itself. There is the possibility, suspected by some scholars, that it was the princes of Guorthegirnaim who supplied the genealogical sections to the Historia Brittonum by Nennius. Nennius states that Ambrosius Aurelianus confirmed Pascent as the first king of Buellt and Guorthegirnaim after the death of Vortigern, thereby confirming the dynasty's subsequent hold on the territories. Supplying the material could have ensured this entry for the dynasty, and may also explain why Guorthegirnaim received extra attention.

Later events after the disappearance of the kingdom of Buellt concerned its former territory, as well as that of Gwrtheyrnion. In the tenth century both were important components of Rhwng Gwy a Hafren ('Between Wye and Severn'), a political entity which is referred to in the poems of Taliesin. Later writers have termed it a kingdom, although it may in fact have enjoyed a less exalted status during its existence. As part of that political entity, and despite actually being to the west of the Wye and therefore an extreme western appendage of Rhwng Gwy a Hafren, Builth was regularly at war with Powys.

(Information by Peter Kessler, with additional information from A History of Wales from the Earliest Times to the Edwardian Conquest, John Edward Lloyd (1912), from the Historia Brittonum (The History of the Britons), Nennius (J A Giles, Ed & Trans, 1841, published as part of Six Old English Chronicles (Henry G Bohn, London, 1848)), from History of the Kings of Britain, Geoffrey of Monmouth, and from External Link: The Definitive Guide To Builth Wells.)

c.406 - 440

Pascent / Pasgen ap Gwrtheyrn

Third son of Vortigern. Given Builth & Gwrtheyrnion by his father.

Geoffrey of Monmouth proposes an almost entirely mythical account of the life of Ambrosius Aurelianus and of Pascent, who remain enemies throughout their lifetimes. Uther Pendragon sets out to attack the Saxons involved in his brother's death, who have teamed up with 'Paschent' and a young nobleman of Ireland named Gillomanius. Uther defeats them all, killing Paschent and Gillomanius.

Romano-Britons burying treasure
With discord building in the country between about 420-450, many Romano-Britons left in a hurry, burying their wealth in the hope that they could return in better times to collect it

c.440 - 475

Braciat / Braigad ap Pasgen


c.440 - 441

Saxon foederati and laeti (settled on the east coast of Britain and in the Thames Valley, and probably increased in number since the barbarian raids on Britain of 409) take advantage of unrest between the two factions trying to govern the country and openly revolt. As a cause they cite the failure of the British to supply them with provisions which may have been reduced to zero as a consequence of the ongoing civil war.

FeatureBy 441, the Gallic Chronicles report large sections of Britain under Germanic control following Saxon revolt: 'Britain, abandoned by the Romans, passed into the power of the Saxons'. Communications between Britain and Gaul are disrupted, vacated towns and cities are in ruin. The migration of Romano-British towards the west and to Armorica turns into a torrent, with emigrants coming especially from Dumnonia and Cornubia. The country begins to be divided geographically, along factional lines.

fl c.442

Morgan ap Pasgen

Brother. Joint ruler?

c.455 - 800

One of the results of the messy situation in the east, following the Jutish foederati takeover of Ceint and the death of Vortigern, is that Gwrtheyrnion now passes to his sole surviving (legitimate) son. Nennius states that this is 'granted' by Ambrosius Aurelianus, but it is probably little more than a rubber stamp. Pascent governs the principality directly from Builth, although he has probably already exercised regional control over it from the point at which it had first been divided from Pagenses. In fact, it would seem that Pascent is already deceased by this time and that it is his son, Braciat, who now governs Built and Gwrtheyrnion - a fine detail that may have been lost to some chroniclers.

c.475 - 510

Idnerth ap Briagad

Son of Braciat.

c.510 - 545

Meuprit / Meurig ap Idnerth



The unchronicled death of Meuprit seems suspiciously close to the mid-century arrival of Yellow Plague in Britain which kills the powerful Maelgwyn of Gwynedd in AD 549. The plague hits the Britons far harder than it does the Germanic invaders, finally shifting the balance of power in favour of the latter. Even the Picts seem to be affected by the plague, with the possible loss of at least one of their kings, Drust mac Munaith, in 552.

c.545 - 580

Pau / Pawl ap Meurig

Son. Sub-king to Brycheiniog for a time.


Caer Gloui, together with Caer Baddan and Caer Ceri, falls to the West Seaxe. With this collapse, the territory of Caer Celemion to the east is now totally isolated, and Dumnonia is cut off from any overland contact with other surviving British territories. Gwent and Pengwern now form the western frontier against further Saxon advances and Buellt is much closer to the danger. The Hwicce take over the fallen West Country territory and eventually push its borders north into Worcestershire, at the expense of Pengwern.

Gloucester's Roman walls
Despite the focus of settlement now being away from the old fort, Glevum's Roman walls were still very much in use in the sixth century when the city fell

c.580 - 615

Eltat / Elaed ap Eldoc ap Pawl

Grandson. At the Battle of Caer Legion (Chester)?


The first meeting between the Roman Church in the form of St Augustine of Canterbury, and the Celtic Church (the descendant of the former British Church of the Roman period) takes place. It is arranged when Ęthelbert of the Cantware uses the Hwicce as intermediaries, and the meeting goes favourably for Augustine.

A second meeting is quickly arranged, although perhaps not in the same year. This takes place at Abberley in Worcestershire, probably close to the border between the Hwicce and Pengwern. It is attended by seven bishops of the Celtic Church, along with many learned monks, mainly from Bangor-is-Coed (in Pengwern). The meeting ends in disappointment for the Roman envoy, with no agreements of cooperation or unity being reached between the two churches, especially in regard to the important question of the calculations for Easter and evangelising the pagan English.


After the death of Keretic (probably Ceretic of Elmet), the high kings of Britain are dominant only in Wales and surviving British western territories. However, even contact with territories such as Dumnonia, Elmet, and Gododdin are becoming tenuous, as the lines of communication are cut. In the first half of the seventh century, the whole of northern Britain is lost, including South Rheged around this time, cutting off Alt Clut, Gododdin, and Galwyddel.

FeatureFurther tragedy is about to strike. In one of the bloodiest and hardest fought battles of its time, several British kings form a coalition to halt Ęthelfrith 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). Iago of Gwynedd and Selyf of Powys are both killed, and the battle is a disastrous British defeat (see one of Geoffrey of Monmouth's more accurate entries about this campaign via the feature link).

c.615 - 650

Moriud / Morwd ap Elaed


633 - 634

Uniquely, perhaps, Penda of Mercia allies himself not to other English kingdoms but to the Brito-Welsh of the west Midlands and Wales. In this year, already working in alliance with Cadwallon of Gwynedd, Penda kills Edwin of Bernicia and Deira at the Battle of Hatfield Chase (just outside the western borders of Lindsey). It seems that, up until this great victory, Penda is the junior partner in the alliance, but following Cadwallon's death in 634 he holds all the cards and is senior partner in the alliance with Pengwern.

c.650 - 685

Guoidcant / Gwyddgan ap Morwd


c.685 - 715

Pascent / Pasgen Buellt


c.715 - 745

Teudor / Tedwr ap Pasgen


fl c.720

Glowd ap Pasgen

Brother. Joint ruler?

fl c.785

Braustud ferch Glowd

Dau. m Arthfael Hen (the Old) of Glywyssing.

c.745 - ?

Fernvail / Ffernfael ap Tewdr

Son of Teudor. Last king of Builth & Gwrtheyrnion

by 800

Fernvail's fate is unknown, as are any firm dates for his life and reign. If the estimate of AD 745 for the start of his reign is remotely accurate then it is unlikely that he lasts as long as 800, but other estimates place him around this later period. A collection of medieval genealogies held in the Bodleian at Oxford - Jesus College MS20 - show him as a contemporary of Arthfael Hen ap Rhys of Glywyssing (Arthfael marries his cousin, Brawstudd, but presumably early in his life rather than later).

River Wye
One of the longest rivers in Britain, the River Wye (Afon Gwy in Welsh) ran along the eastern edge of Buellt, dividing it from Powys on the other side

This king can be placed anywhere in the last quarter of the eighth century and first quarter of the ninth century, so using AD 800 as a rough point for the presumed death of Fernvail seems appropriate. Afterwards, Builth and Gwrtheyrnion cease to exist as separate Welsh territories in their own right, being absorbed by Seisyllwg and then Deheubarth. The precise circumstances and process by which this happens are unknown. They re-emerge in the tenth century as parts of the political formation known as Rhwng Gwy a Hafren.