'''Northumbria''' was an Anglian kingdom of the [[Heptarchy]] period. At its territorial peak, covering a large area the kingdom covered almost all of what is now modern-day northern [[England]] and southern south-east [[Scotland]], plus a large part of south-west Scotland as well. At its peakThe kingdom was bound by the [[Firth of Forth]] in the north, it extended with the southern boundary running from the Rivers estuaries of the [[River Humber|Humber]] (with the kingdom/ethnic name ''Norþanhymbre'' meaning "north (of the) Humber") and [[River Mersey|Mersey]] (indeed, ''Mersey'' is derived from the [[Old English]] ''mæres ēa'', "boundary river"); the southern border in particular is known to have fluctuated, however. Northumbria existed as an independent kingdom between the south years 651–867 AD. Despite ceasing to exist as an independent territory over 1000 years ago, the Firth kingdom has had an everlasting legacy. The county-name of Forth [[Northumberland]], despite that covering a far smaller area, is descended directly from the kingdom name. [[Northumbria (modern)|Northumbria]] is an informal and loosely-defined region of England, sometimes used as a synonym for [[North East England]], the northern shores heartland of the ancient kingdom, with its inhabitants still sometimes being referred to as "Northumbrians". [[Solway FirthNorthumbria University]] , Northumbria Police and Northumbrian Water (all based in the northNorth East) also take their name from the kingdom.== Geographical extent ==At its greatest geographical extent (c. 700 AD), the kingdom broadly consisted of the present-day English counties [[Cumberland]], [[County Durham]], [[Lancashire]], [[Northumberland]], [[Westmorland]] and [[Yorkshire]], as well as [[Berwickshire]], [[Dumfriesshire]], [[Kirkcudbrightshire]], the [[Lothian|Lothians]], [[Roxburghshire]], [[Selkirkshire]] and [[Wigtownshire]] in Scotland. The Kingdom of Northumberland, starting in the 7th century, may have periodically ruled Lindsey in [[Lincolnshire]].
== History of Northumbria ==
The Kingdom of Northumbria was formed by the union of the kingdoms of Bernicia (north of the River [[River Tees|Tees]]) and Deira (south of the Tees, roughly corresponding with the county of [[Yorkshire]]). Berniccia was traditionally founded by the Anglian chieftain Ida who seized the coastal strong point of Bamburgh in AD 547, and from that point conquered what is now modern [[Northumberland]]. More recent scholarship suggests that Bernicia developed as a Celtic-Anglian kingdom, with centres of kingship at Bamburgh, Yeavering and Millfield.
The kingdoms of Bernicia and Deira were united under Aethelfrith of Bernicia in 604; he was killed in battle in 616 and replaced by Edwin, the son of a former king of Deira. He converted to Christianity and became the most powerful ruler in Britain, expanding Northumbrian territory by conquering the [[Isle of Man]] and parts of north [[Wales]]; however, his enemies combined against him and he was killed in 633. Edwin's death led to a period of warfare and fragmentation of the kingdom, but it was reunited after 634 under the exiled Bernician noble Oswald, who, backed by troops of the Irish kingdom of [[Dalriada]] (where he had lived in exile), defeated the Welsh king Cadwallon at the Battle of Heavenfield, near [[Hadrian's Wall]] in [[Northumberland]], in 634. Before the battle, Oswald raised a cross and with his soldiers prayed for victory. Oswald was himself killed in battle in 642 by Penda of [[Mercia]]. Penda attacked Northumbria in 655, but was defeated by the Northumbrian king Oswiu. Oswiu's son Ecgfrith attempted to extend Northumbrian power into Pictland (eastern Scotland) but was killed in battle in 685; from that point Northumbrian political supremacy waned rapidly. The kingdom was damaged by Viking attacks and in the ninth century by the formation of the Viking Kingdom of York in Deira. In the resurgent English kingdom that gradually overcame Viking power, Northumbria was reduced to the status of an earldom, while growing Scottish power deprived it of its northern territories. The Northumbrian-Scottish border was settled on the River Tweed in 1028.