1911 Encyclopædia Britannica/Bernicia
BERNICIA, the northern of the two English kingdoms which were eventually united in the kingdom of Northumbria. Its territory is said to have stretched from the Tyne northwards, ultimately reaching the Forth, while its western frontier was gradually extended at the expense of the Welsh. The chief royal residence was Bamburgh, and near it was the island of Lindisfarne, afterwards the see of a bishop. The first king of whom we have any record is Ida, who is said to have obtained the throne about 547. Æthelfrith, king of Bernicia, united Deira to his own kingdom, probably about 605, and the union continued under his successor Edwin, son of Ella or Ælle, king of Deira. Bernicia was again separate from Deira under Eanfrith, son of Æthelfrith (633-634), after which date the kings of Bernicia were supreme in Northumbria, though for a short time under Oswio Deira had a king of its own.
See Bede, Hist. Eccles. ii. 14, iii. 1, 14; Nennius, § 63; Simeon of Durham, i. 339.