under the suzerainty of Denmark and the Holy Roman Empire in the late 12th century. Gdańsk, established during the reign of Mieszko I of Poland has since become Poland's main port (apart from periods of Poland losing control over the region). In the 12th century, the Duchy of Pomerania (western part), as a vassal state of Poland, became Christian under saint Otto of Bamberg (the Apostle of the Pomeranians); at the same time Pomerelia (eastern part) became a part of diocese of Włocławek within Poland. Since the late 12th-early 13th century, the Griffin Duchy of Pomerania stayed with the Holy Roman Empire and the Principality of Rugia with Denmark, while Pomerelia, under the ruling of Samborides, was a part of Poland. Pomerania, during its alliance in the Holy Roman Empire, shared borders with West Slavic state Oldenburg, as well as Poland and the expanding Margraviate of Brandenburg. In the early 14th century the Teutonic Knights invaded and annexed Pomerelia from Poland into their monastic state, which already included historical Prussia. As a result of the Teutonic rule, in German terminology the name of Prussia was also extended to conquered Polish lands like Gdańsk Pomerania, although it was not inhabited by Baltic Prussians but Lechitic Poles. Meanwhile, the Ostsiedlung started to turn Slavic narrow Pomerania into an increasingly German-settled area; the remaining Wends and Polish people, often known as Kashubians, continued to settle within Pomerelia. In 1325 the line of the princes of Rügen died out, and the principality was inherited by the Griffins. Renaissance (circa 1400–1700) to Early Modern Age In 1466, with the Teutonic Order's defeat in the Thirteen Years' War, Pomerelia became again subject to the Polish Crown and formed the Pomeranian Voivodeship within the province of Royal Prussia. While the German population in the Duchy of Pomerania adopted the Protestant reformation in 1534, the Polish (along with Kashubian) population remained with the Roman Catholic Church. The Thirty Years' War severely ravaged and depopulated narrow Pomerania; few years later this same happened to Pomerelia (the Deluge). With the extinction of the Griffin house during the same period, the Duchy of Pomerania was divided between the Swedish Empire and Brandenburg-Prussia in 1648, while Pomerelia remained in with the Polish Crown. Modern Age Prussia gained the southern parts of Swedish Pomerania in 1720, invaded and annexed Pomerelia from Poland in 1772 and 1793, and gained the remainder of Swedish Pomerania