County of Mark
Hagen was first mentioned around the year 1200, and is presumed to have been the name of a farm at the confluence of the Volme and the Ennepe rivers. After the conquest of Burg Volmarstein in 1324, Hagen passed to the County of Mark. In 1614 it was awarded to the Margraviate of Brandenburg, according to the Treaty of Xanten. In 1701 it became part of the Kingdom of Prussia.