Bernicia stretched from the Tees north to the Firth of Forth and, at its greatest extent, to beyond the Solway Firth. There is no agreed derivation for the name. Jackson suggests the Celtic *berna 'gap, mountain pass' which may have developed through *bernia to *bernicia. In this case the name may have been coined for the Stainmoor region. The eastern region was the old tribal land of the Votodani and the Brigantes.

The territory south of Hadrian's wall would have been under Roman military government until the collapse of the Imperial government in Britain. Consequently the newcomers were faced by a British society touched only lightly by Romano-British civilization. Repeated raids across the region by the Picts before and after the Roman withdrawal, will have left it impoverished and disorganised.

There are strong indications of Celtic survival in the Bernician region and it is possible that the Angles were a small fighting aristocracy seeking to dominate the native population rather than land-seeking settlers.

Lindisfarne (Metcaud) and Bamborough were occupied early. It is probable that the first foothold was at Bamborough and that the Anglian group that made this settlement originated in the main Anglian settlement areas in Deira and south of the Humber.