Soon after AD 603, King Ethelfrith of Bernicia (about 593-616) took over the kingdom of Deira to the south, forming the large realm of Northumbria in north-east England. On Ethelfrith’s death, the throne was taken by Edwin of Deira (616-33) and the Bernician royal family went into exile in Scotland. The Bernician line was restored with Oswald (634-42) who pursued an aggressively expansionist policy, so that by the reign of Ecgfrith (670-85) the Northumbrian king’s authority reached the Firth of Forth in Scotland and Lincolnshire in the south.

Meanwhile King Oswald had invited an Irish mission from Iona (Scotland) to bring Christianity to the country. A monastery was built on the Isle of Lindisfarne in 635. This was the beginning of the great age of Northumbrian Christianity and the brilliant monastic culture that was at its heart. The kingdom of Northumbria prospered until the end of the 8th century when it was repeatedly attacked and its wealthy monasteries pillaged by Viking raiders from Scandinavia. Full-scale settlement followed and the kingdom was fragmented. A Viking kingdom based on York was only restored to English rule by Alfred the Great’s descendants in 954.