the Silesian Przesieka and the Silesia Walls. The eastern border of Silesian settlement was situated to the west of the Bytom, and east from Racibórz and Cieszyn. East of this line dwelt a closely related Lechitic tribe, the Vistulans. Their northern border was in the valley of the Barycz River, north of which lived the Western Polans tribe who gave Poland its name. The first known states in Silesia were Greater Moravia and Bohemia. In the 10th century, the Polish ruler Mieszko I of the Piast dynasty incorporated Silesia into the newly established Polish state. In 1000, the Diocese of Wrocław was established as the oldest Catholic diocese in the region, and one of the oldest dioceses in Poland, subjugated to the Roman Catholic Archdiocese of Gniezno. Poland repulsed German invasions of Silesia in 1017 at Niemcza and in 1109 at Głogów. During the Fragmentation of Poland, Silesia and the rest of the country were divided into many smaller duchies ruled by various Silesian dukes. During this time, German cultural and ethnic influence increased as a result of immigration from German-speaking states of the Holy Roman Empire. In 1178, parts of the Duchy of Kraków around Bytom, Oświęcim, Chrzanów, and Siewierz were transferred to the Silesian Piasts, although their population was primarily Vistulan and not of Silesian descent. In 1241, the Mongols conducted their first invasion of Poland, causing widespread panic and mass flight. They looted much of the region and defeated the combined Polish, Moravian and German forces led by Duke Henry II the Pious at the Battle of Legnica, which took place at Legnickie Pole near the Silesian city of Legnica. Upon the death of Orda Khan, the Mongols chose not to press forward further into Europe, but returned east to participate in the election of a new Grand Khan (leader). Between 1289 and 1292, Bohemian king Wenceslaus II became suzerain of some of the Upper Silesian duchies. Polish monarchs had not renounced their hereditary rights to Silesia until 1335. The province became part of the Bohemian Crown which was part of the Holy Roman Empire; however, a number of duchies remained under the rule of the Polish dukes from the houses of Piast, Jagiellon and Sobieski as formal Bohemian fiefdoms, some until the 17th–18th centuries. In 1469 sovereignty over the region passed to Hungary, and in 1490 it returned to Bohemia. In 1526 Silesia passed with the