On 12 July 927, the various Anglo-Saxon kingdoms were united by Æthelstan (r. 927–939) to form the Kingdom of England. In 1016, the kingdom became part of the North Sea Empire of Cnut the Great, a personal union between England, Denmark and Norway. The Norman conquest of England in 1066 led to the transfer of the English capital city and chief royal residence from the Anglo-Saxon one at Winchester to Westminster, and the City of London quickly established itself as England's largest and principal commercial centre.