 Athelstan took the submission of some of these other kings, presumably to form some sort of coalition against the Vikings.The growing power of the Scots and perhaps also of the Strathclyders, may have persuaded Athelstan to move north and attempt to define the boundaries of the various kingdoms.This is generally seen as the date of the foundation of the Kingdom of England, the northern boundary of which was the Eamont river (with Westmorland being outside the control of Strathclyde).