Bernicia occurs in Old Welsh poetry as Bryneich or Brynaich and in the 9th-century Historia Brittonum, as Berneich or Birneich. This was most likely the name of the native Brittonic kingdom, whose name was then adopted by the Anglian settlers who rendered it in Old English as Bernice or Beornice. The counter hypothesis suggesting these names represent a Brythonic adaption of an earlier English form is considered less probable. Local linguistic evidence suggests continued political activity in the area before the arrival of the Angles. Important Anglian centres in Bernicia bear names of British origin, or are known by British names elsewhere: Bamburgh is called Din Guaire in the Historia Brittonum; Dunbar represents Dinbaer; and the name of Coldingham is given by Bede as Coludi urbs, where Colud seems to represent the British form, possibly for the hill-fort of St Abb's Head. Analysis of a potential derivation has not produced a consensus. The most commonly cited etymology gives the meaning as "Land of the Mountain Passes" or "Land of the Gaps". An earlier derivation from the tribal name of the Brigantes has been dismissed as linguistically unsound. In 1997 John T. Koch suggested the conflation of a probable primary form *Bernech with the native form *Brïγent for the old civitas Brigantum as a result of Anglian expansion in that territory during the 7th century.
The Brythonic kingdom of the area was formed from what had once been the southern lands of the Votadini, possibly as part of the division of a supposed 'great northern realm' of Coel Hen in c. AD 420. This northern realm is referred to by Welsh scholars as Yr Hen Ogledd or, literally, "The Old North". The kingdom may have been ruled from the site that later became the English Bamburgh, which certainly features in Welsh sources as Din Guardi. Near this high-status residence lay the island of Lindisfarne, which became the seat of the Bernician bishops. It is unknown when the Angles finally conquered the whole region, but around 604 is likely.
Kings of British Bryneich
There are several Old Welsh pedigrees of princely "Men of the North" that may represent the kings of the British kingdom in the area, which may have been called Bryneich. John Morris surmised that the line of a certain Morcant Bulc referred to these monarchs, chiefly because he identified this man as the murderer of Urien Rheged who was, at the time, besieging Lindisfarne.
English Bernicia
Some of the Angles of Bernicia may have been employed as mercenaries along Hadrian's Wall during the late Roman period. Others are thought to have migrated north from Deira in the early 6th century. The first Anglian king in the historical record is Ida, who is said to have obtained the throne and the kingdom about 547. His sons spent many years fighting a united force from the surrounding Brythonic kingdoms until their alliance collapsed into civil war.
A forcibly united Northumbria
Ida's grandson, Æthelfrith, united Deira with his own kingdom by force around the year 604. He ruled the two kingdoms until he was defeated and killed by Rædwald of East Anglia around the year 616. Edwin then became king. The early part of Edwin's reign was possibly spent finishing off the remaining resistance coming from the Brythonic exiles of the old British kingdom, operating out of Gododdin. After he had defeated the remaining Brythonic population of the area, he was then drawn towards a similar subjugation of Elmet, which drew him into direct conflict with Wales proper. Following the disastrous Battle of Hatfield Chase on 12 October 633, in which Edwin was defeated and killed by Cadwallon ap Cadfan of Gwynedd and Penda of Mercia, Northumbria was divided back into Bernicia and Deira. Bernicia was then briefly ruled by Eanfrith, son of Æthelfrith, but after about a year he went to Cadwallon to sue for peace and was killed. Eanfrith's brother Oswald then raised an army and finally defeated Cadwallon at the Battle of Heavenfield in 634. After this victory, Oswald appears to have been recognised by both Bernicians and Deirans as king of a properly united Northumbria. The kings of Bernicia were thereafter supreme in that kingdom, although Deira had its own sub-kings at times during the reigns of Oswiu and his son Ecgfrith.
