Northumberland is where Roman occupiers once guarded a walled frontier, Anglian invaders fought with Celtic natives, and Norman lords built castles to suppress rebellion and defend a contested border with Scotland.
The present-day county is a vestige of an independent Northern English kingdom that once stretched from Edinburgh to the River Humber. Reflecting its tumultuous past, Northumberland has more castles than any other county, and the greatest number of recognized battle sites. Once an economically important region that supplied much of the coal that powered the industrial revolution, Northumberland is now a rural county with a small and gradually shrinking population.
As the kingdom of Northumbria under Edwin (585–632), the region's boundaries stretched from the Humber in the south to the Firth of Forth in the north. Being on the border of England and Scotland, Northumberland has been the site of many battles.
The county is noted for its undeveloped landscape of high moorland, a favourite with landscape painters, and now largely protected as a National park. Northumberland is the most sparsely populated county in England, with only 62 people per square kilometre. This is mainly because the large cities of Newcastle upon Tyne and Tynemouth were joined to Gateshead and Sunderland in the metropolitan county of Tyne and Wear.
- Long B. 1967. Castles of Northumberland. Newcastle: Harold Hill.
- Dowson J. 2009. Northumberland's economy 2009. Northumberland Information Network