The German surname Schirmer emerged in the lands that formed the powerful German state of Prussia, which at one time was an immense German territory that stretched from France and the Low Countries to the Baltic sea and Poland. After the fall of the Roman Empire, the German territories were inhabited by a variety of Barbarian tribes. The borders of the Barbarian kingdoms changed frequently, but the region that became known as Prussia was roughly divided between the areas of Brandenburg-Prussia, West Prussia, and East Prussia. Brandenburg-Prussia was essentially the birthplace of modern Germany. By the 19th century, Brandenburg-Prussia had incorporated East Prussia, West Prussia and many other German territories. Moreover, in the late 19th century, it led the German states in German Unification.