Northumberland, county, extreme northeastern England. Morpeth serves as the administrative center. Northumberland comprises a coastal plain in the east along the North Sea and an upland area of hills and moors in the west. The Cheviot Hills extend along the Scottish border in the north. Agriculture and livestock raising are the chief occupations. In Northumberland are remains of Hadrian's Wall, constructed by the Romans in the 2nd century ad. In the 7th century the region formed part of the Anglo-Saxon kingdom of Northumbria. Until the union of England with Scotland (1603), the county suffered repeatedly from border wars.