Deira

Deira (Old English: Derenrice (Scandinavian: Deren Riket; Germanic Deren Reich) or Dere) was a kingdom in Northern England which probably emerged when Anglian warriors conquered the Derwent Valley in the third quarter of the fifth century. It extended from the Humber to the Tees, and from the sea to the western edge of the Vale of York. It was the southern of the two kingdom of Deira and Bernicia which later merged to form the kingdom of Northumbria.

The name of the kingdom is of Brythonic origin, perhaps from Deifr, meaning "waters", or from Daru, meaning "oak", in which case it would mean "the people of the Derwent", a derivation also found in the Latin name for Malton, Derventio.

According to Simeon of Durham it extended from the Humber to the Tyne, but the land was waste north of the Tees. After the Brythonic kingdom centered around Eboracum, which may have been called Ebrauc, was taken by Edwin, the city of Eboracum became its capital and was called Eoforwic (boar-place) by the Angles. Before this it is likely that the capital would have been at or near Pocklington.

The first Deiran Anglian king of whom we have any record is Ælla, who flourished in the later 6th century after conquering the realm from the Britons in 581. After his death, Deira was subject to king Æthelfrith of Bernicia, who united the two kingdoms into Northumbria. Æthelfrith ruled until the accession of Ælla's son Edwin, in 616 or 617, who also ruled both kingdoms until 633.

Osric, the nephew of Edwin, ruled Deira after Edwin, but his son Oswine was put to death by Oswiu in 651. For a few years subsequently Deira was governed by Æthelwald son of Oswald of Bernicia.

Bede wrote of Deira in his Historia Ecclesiastica.