Northumbria was formed in central Great Britain in Anglo-Saxon times. At the beginning of the 7th century the two kingdoms of Bernicia and Deira were unified. (In the 12th century writings of Henry of Huntingdon the kingdom was defined as one of the Heptarchy of Anglo-Saxon kingdoms.) At its greatest the kingdom extended at least from just south of the Humber, to the River Mersey and to the Forth (roughly, Sheffield to Runcorn to Edinburgh) - and there is some evidence that it may have been much greater (see map).
The later (and smaller) earldom came about when the southern part of Northumbria (ex-Deira) was lost to the Danelaw. The northern part (ex-Bernicia) at first retained its status as a kingdom but when it become subordinate to the Danish kingdom it had its powers curtailed to that of an earldom, and retained that status when England was reunited by the Wessex-led reconquest of the Danelaw. The earldom was bounded by the River Tees in the south and the River Tweed in the north (broadly similar to the modern North East England). Much of this land was "debated" between England and Scotland, but the Earldom of Northumbria was eventually recognised as part of England by the Anglo-Scottish Treaty of York in 1237. On the northern border, Berwick-upon-Tweed, which is north of the Tweed but had changed hands many times, was defined as subject to the laws of England by the Wales and Berwick Act of 1746.
The land once part of Northumbria at its peak is now divided by modern administrative boundaries.
In a modern sense, Northumbria is mainly used as a romantic tourist name for the North East of England, or, often, just for Northumberland, though the regional tourist organisation refers to North East England. It is also used in the names of some regional institutions : particularly the police force (Northumbria Police) which covers Northumberland and Tyne and Wear) and a university Northumbria University based in Newcastle. The local Environment Agency office, located in Newcastle Business Park, also uses the term Northumbria to describe its patch. Otherwise, the term is not used in everyday conversation, and is not the official name for the UK and EU region of North East England.
Edwin, who accepted Christianity in 627, soon grew to become the most powerful king in England: he was recognized as Bretwalda and conquered the Isle of Man and Gwynedd in northern Wales. He was, however, himself defeated by an alliance of the exiled king of Gwynedd, Cadwallon ap Cadfan and Penda, king of Mercia, at the Battle of Hatfield Chase in 633.
Oswald expanded his kingdom considerably. He incorporated Gododdin lands northwards up to the Firth of Forth and also gradually extended his reach westward, encroaching on the remaining Cumbric speaking kingdoms of Rheged and Strathclyde. Thus, Northumbria became not only part of modern England's far north, but also covered much of what is now the south-east of Scotland.
King Oswald re-introduced Christianity to the Kingdom by appointing St. Aidan, an Irish monk from the Scottish island of Iona to convert his people. This led to the introduction of the practices of Celtic Christianity. A monastery was established on Lindisfarne.
War with Mercia continued, however. In 642, Oswald was killed by the Mercians under Penda at the Battle of Maserfield. In 655, Penda launched a massive invasion of Northumbria, aided by the sub-king of Deira, Aethelwald, but suffered a crushing defeat at the hands of an inferior force under Oswiu, Oswald's successor, at the Battle of Winwaed. This battle marked a major turning point in Northumbrian fortunes: Penda died in the battle, and Oswiu gained supremacy over Mercia, making himself the most powerful king in England.
Northumbria lost control of Mercia in the late 650s, after a successful revolt under Penda's son Wulfhere, but it retained its dominant position until it suffered a disastrous defeat at the hands of the Picts at the Battle of Nechtansmere in 685; Northumbria's king, Ecgfrith (son of Oswiu), was killed, and its power in the north was gravely weakened. The peaceful reign of Aldfrith, Ecgfrith's half-brother and successor, did something to limit the damage done, but it is from this point that Northumbria's power began to decline, and chronic instability followed Aldfrith's death in 704.
In 867 Northumbria became the northern kingdom of the Danelaw, after its conquest by the brothers Halfdan Ragnarsson and Ivar the Boneless who installed an Englishman, Ecgberht, as a puppet king. Despite the pillaging of the kingdom, Viking rule brought lucrative trade to Northumbria, especially at their capital Jórvík, (York).
Rebellions continued, and William's son William Rufus decided to partition Northumbria. William of St. Carilef was made Bishop of Durham, and was also given the powers of Earl for the region south of the rivers Tyne and Derwent, which became the County Palatine of Durham. The remainder, to the north of the rivers, became Northumberland, where the political powers of the Bishops of Durham were limited to only certain districts, and the earls continued to rule as clients of the English throne.
The city of Newcastle was founded by the Normans in 1080 to control the region by holding the strategically important crossing point of the river Tyne.
The flag of the kingdom was "a banner made of gold and purple" (or red), first recorded in the 8th century as having hung over the shrine of King Oswald. This was later interpreted as vertical stripes. A modified version (with broken vertical stripes) can be seen in the coat of arms and flag used by Northumberland County Council.
Northumbria has its own check or tartan, which is similar to many ancient tartans (especially those from Northern Europe, such as one found near Falkirk and those discovered in Jutland that date from Roman times (and even earlier). Modern Border Tartans are almost invariably a bold black and white check, but historically the light squares were the yellowish colour of untreated wool, with the dark squares any of a range of dark grays, blues, greens or browns; hence the alternative name of "Border Drab." At a distance the checks blend together making the fabric ideal camouflage for stalking game.
The major Northumbrian dialects are Geordie (Tyneside), Northern (north of the River Coquet), Western (from Allendale through Hexham up to Kielder), Southern or Pitmatic (the mining towns such as Ashington and much of Durham), Mackem (Wearside), Smoggie (Teesside) and Tyke. To an outsider's ear the similarities far outweigh the differences between the dialects. As an example of the difference in the softer South County Durham/Wearside the English 'book' is pronounced 'bewk', in Geordie it becomes 'bouk' while in the Northumbrian it is 'byuk'.
Due to the roots of Northumbrian dialects, it is often said that visitors from Scandinavian countries and the Netherlands often find it much easier to understand the English of Northumbria than the rest of the country. An example is the Geordie 'gan hyem' (to go home), which sounds similar to the Danish and Norwegian 'gå hjem', and means the same. In fact, many northeasterners report that when abroad they are often mistaken for Norwegians or Danes. This occurance is said to be particularly common with German speakers.