https://en.wikipedia.org/wiki/List_of_monarchs_of_Northumbria
Northumbria, a kingdom of Angles, in what is now northern England and south-east Scotland, was initially divided into two kingdoms: Bernicia and Deira.The two were first united by king Æthelfrith around the year 604, and except for occasional periods of division over the subsequent century, they remained so. The exceptions are during the brief period from 633 to 634, when …