In 1921–1922 the borders of the Second Polish Republic were finally established. Upper Silesia was divided (see: Silesian Uprisings) and the boundary left in German hands several crucial junctions, including Kluczbork (Kreuzburg) and Fosowskie (Vossowska). Without these centers, rail communication between Polish Silesia and the Baltic Sea was virtually impossible. As coal was one of the main Polish exports, and transit through Germany was not allowed (due to the German–Polish customs war in the late 1920s and early 1930s), construction of the new line was necessary.