The history of Pomerania starts shortly before 1000 AD with ongoing conquests by newly arrived Polans rulers. Before that, the area was recorded nearly 2000 years ago as Germania, and in modern-day times Pomerania is split between Germany and Poland. Its name comes from the Slavic po more, which means "land at the sea". Settlement in the area started by the end of the Vistula Glacial Stage, about 13,000 years ago. Archeological traces have been found of various cultures during the Stone and Bronze Age, of Veneti and Germanic peoples during the Iron Age and, in the Middle Ages, Slavic tribes and Vikings. Starting in the 10th century, Piast Poland on several occasions acquired parts of the region from the south-east, while the Holy Roman Empire and Denmark reached the region in augmenting their territory to the west and north. In the High Middle Ages, the area became Christian and was ruled by local dukes of the House of Pomerania and the Samborides, at various times vassals of Denmark, the Holy Roman Empire and Poland. From the late 12th century, the Griffin Duchy of Pomerania stayed with the Holy Roman Empire and the Principality of Rügen with Denmark, while Denmark, Brandenburg, Poland and the Teutonic Knights struggled for control in Samboride Pomerelia. The Teutonic Knights succeeded in annexing Pomerelia to their monastic state in the early 14th century. Meanwhile, the Ostsiedlung started to turn Pomerania into a German-settled area; the remaining Wends, who became known as Slovincians and Kashubians, continued to settle within the rural East. In 1325, the line of the princes of Rügen died out, and the principality was inherited by the House of Pomerania, themselves involved in the Brandenburg-Pomeranian conflict about superiority in their often internally divided duchy. In 1466, with the Teutonic Order's defeat, Pomerelia became subject to the Polish Crown as a part of Royal Prussia. While the Duchy of Pomerania adopted the Protestant Reformation in 1534, as part of the Empire by then termed the Holy Roman Empire of the German Nation, Kashubia remained with the Roman Catholic Church. The Thirty Years' and subsequent wars severely ravaged and depopulated most of Pomerania. 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. Prussia gained the southern parts of Swedish Pomerania in 1720. It gained the remainder of Swedish Pomerania