North West England includes Cumbria, though Cumbria was more of a Northumbrian colony with its own client kings for most of its history in the Early Medieval era Scottish Borders, West Lothian, Edinburgh, Midlothian and East Lothian cover the extreme north .
In a modern sense, Northumbria is mainly used as a romantic tourist name for the North East of England, or, often, just for Northumberland, though the regional tourist organisation refers to North East England. It is also used in the names of some regional institutions: particularly the police force (Northumbria Police) which covers Northumberland and Tyne and Wear) and a university Northumbria University based in Newcastle. The local Environment Agency office, located in Newcastle Business Park, also uses the term Northumbria to describe its patch. Otherwise, the term is not used in everyday conversation, and is not the official name for the UK and EU region of North East England.
Northumbria was originally composed of the union of two independent kingdoms, Bernicia and Deira. Bernicia covered lands north of the Tees, whilst Deira corresponded roughly to modern-day Yorkshire. Bernicia and Deira were first united by Aethelfrith, a king of Bernicia who conquered Deira around the year 604. He was defeated and killed around the year 616 in battle at the River Idle by Raedwald of East Anglia, who installed Edwin, the son of Aella, a former king of Deira, as king.
Edwin, who accepted Christianity in 627, soon grew to become the most powerful king in England: he was recognized as Bretwalda and conquered the Isle of Man and Gwynedd in northern Wales. He was, however, himself defeated by an alliance of the exiled king of Gwynedd, Cadwallon ap Cadfan and Penda, king of Mercia, at the Battle of Hatfield Chase in 633.