The Goplanie (Polish tribe) made their home on the shores of Lake Gopło. At the northern end of the lake is situated the Mouse Tower of Kruszwica (Mysia Wieża). Legend persists that it was named after the Prince Popiel, who rejected his people and for his oversight was devoured by mice in the tower. It is thought by some historians and archaeologists to have been the heart of the first Polanie state when the the latter emerged in the sources in the time of Mieszko I (died 992).