The Kingdom of England was a sovereign state on the island of Great Britain from the 10th century (when it emerged from various Anglo-Saxon kingdoms) until 1707, when it united with Scotland to form the Kingdom of Great Britain.

In the early 10th century the Anglo-Saxon kingdoms 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.

More Info: en.wikipedia.org