Northumbria (Old English: Norþanhymbra / Norþhymbre) was a mediaeval kingdom of the Angles, in what is now Northern England and South-East Scotland, becoming subsequently an earldom in a united Anglo-Saxon Kingdom of England. The name reflects the approximate southern limit to the kingdom's territory, the Humber estuary.
Northumbria was formed by Æthelfrith 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).