 The reign of Aethelfrith's rival, brother-in-law and successor, Edwin, saw Northumbrian power stretch as far as the 'Irish Sea Province' with the taking of the Isle of Man (c. 624) and Anglesey.How much involvement Rheged had in this move is unclear.Northumbrian ambitions were eventually checked with the disastrous defeat of King Ecgfrith's forces in 685 at the hands of the Picts at the Battle of Dun Nechtain, but the north-west region, including the Cumbria area, remained firmly within the Northumbrian ambit during this period.