Oswald and Oswiu returned to Northumbria after Edwin's death in 633, and between them they ruled for much of the middle of the 7th century. The 8th-century monk and chronicler Bede lists both Oswald and Oswiu as having held "imperium", or overlordship, over the other Anglo-Saxon kingdoms; in Oswiu's case his dominance extended beyond the Anglo-Saxons to the Picts, the Gaels of Dál Riata, and the many obscure and nameless native British kingdoms in what are now North West England and southern Scotland. Oswiu's overlordship was ended in 658 by the rise of Wulfhere of Mercia, but his reign continued until his death in 670, when Ecgfrith, one of his sons by his second wife, Eanflæd, succeeded him. Ecgfrith was unable to recover Oswiu's position in Mercia and the southern kingdoms, and was defeated by Wulfhere's brother Æthelred in a battle on the River Trent in 679.