Northumbria was an Anglian kingdom of the Heptarchy period, covering a large area of what is now northern England and southern Scotland. At its peak, it extended from the Rivers Humber and Mersey in the south to the Firth of Forth and the northern shores of the Solway Firth in the north.
History of Northumbria
The Kingdom of Northumbria was formed by the union of the kingdoms of Bernicia (north of the River 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.
Oswald invited Celtic monks from Iona under Aidan to form a monastery on Holy Island (Lindisfarne); between 650 and 750 Northumbrian monasticism was an intellectual beacon in northern Europe