Northumbria ( was an early medieval kingdom in what is now Northern England and South Scotland. The name derives from the Old English Norþanhymbre meaning "the people or province north of the Humber", as opposed to the people south of the Humber Estuary. What was to become Northumbria started as two kingdoms, Deira in the south and Bernicia in the north. Conflict in the first half of the seventh century ended with the murder of the last king of Deira in 651, and Northumbria was thereafter unified under Bernician kings. .
https://en.wikipedia.org/wiki/Northumbria