The area was already inhabited in the Stone Age. In the Middle Ages the Moryń peninsula had been the site of a West Slavic fortress. Inhabited by the Polish tribes, in the 10th century it was included in the emerging Polish state, part of which it remained until the late 13th century, when it was annexed by the Margraviate of Brandenburg. The settlement was first mentioned in medieval documents in 1263. It was mentioned as a town in 1306. The fortress was rebuilt in 1365 by Wittelsbach elector Otto V of Brandenburg. In 1373, with the New March region it became part of the Czech (Bohemian) Crown Lands, ruled by the Luxembourg dynasty. In 1402, the Luxembourgs reached an agreement with Poland in Kraków, according to which Poland was to purchase and re-incorporate the region, but eventually the Luxembourgs pawned it to the Teutonic Order. During the Polish–Teutonic War (1431–1435) the town was devastated during a Hussite campaign in 1433. When another Polish-Teutonic war broke out in 1454, the Teutonic Knights sold the region to Brandenburg in order to raise funds for war.