Mieszko II Lambert
Since the 9th century, the stronghold was fortified and expanded toward the Oder bank. Mieszko I of Poland took control of Pomerania during the Early Middle Ages and the region became part of Poland in the 10th century. However, already Mieszko II Lambert (1025 ~ 1034) effectively lost control over the area and had to accept German suzerainty over the area of the Oder lagoon. Subsequent Polish rulers, the Holy Roman Empire, and the Liutician federation all aimed to control the territory.