The British empire was an empire ruled by the island of Great Britain, including Scottish and Welsh dynasties intermarried with the English dynasty descended from William the Conqueror. At it's height it ruled much of North America, Ireland, Cornwall, the Faeroe Islands and the Netherlands
Besides Wales & Scotland, Cornwall joined the empire because of the marriage of Gwendolyn of Cornwall to king James in 1588, originally as a strategic alliance against England. Their son, Peter, born in 1597, married Hannah of Orange in 1618. By this time they had begun founding colonies in North America. Their only son, Edgar, died childless after only six years on the throne. His cousin Joanne, daughter of Prince Andrew, then inherited the throne. She had married John of Somerset the year before.