The Swedish Empire, referred to in Sweden as the Great Power era, was the period in Swedish history spanning much of the 17th and early 18th centuries during which Sweden was a European great power that exercised territorial control over much of the Baltic region. During this period it also held territories on the North Sea and some overseas colonies, including New Sweden. The beginning of the period is usually taken as the reign of Gustavus Adolphus, who ascended the throne in 1611, and its end as the loss of territories in 1721 following the Great Northern War.