The Kingdom of Northumbria was a medieval Anglian kingdom in what is now northern England and southeastern Scotland in the United Kingdom. The name derives from the Old English Norþan-hymbre meaning "the people or province north of the Humber Estuary". Northumbria started to consolidate into one kingdom in the early 7th century, when the two earlier core territories of Deira and Bernicia entered into a dynastic union. At its height, the kingdom extended from the Humber, Peak District and the River Mersey on the south to the Firth of Forth (now in Scotland) on the north. Northumbria ceased to be an independent kingdom in the mid-10th century, though a rump Earldom of Bamburgh survived around Bernicia in the north, later to be absorbed into the medieval kingdoms of Scotland and England.
Today, Northumbria is an unofficial term referring to a cluster of northeast English counties including Northumberland, Durham, Tyne, and Wear.
Northumbria in "The Pugnacious Peacemaker"
While Northumbria traditionally had good relations with Tawantiinsuuju, in 1941 it was reluctant to support the latter's audacious claim to certain lands also claimed by the Emirate of the dar al-Harb.