Prior to World War II it was part of Germany . During the Yalta Conference it was discussed by the Western Allies as one possible line of the western Polish border . Attempts were made to negotiate a compromise with the Soviets on the new Polish-German frontier ; it was suggested that the Eastern Neisse be made the line of demarcation . This would have meant that ( East ) Germany could have retained approximately half of Silesia , including most of Wrocław ( formerly Breslau ) . However the Soviets rejected the suggestion at the Potsdam Conference and insisted that the southern boundary between Germany and Poland be drawn further west , at the Lusatian Neisse
Yalta Conference
Yalta Conference
Eastern Neisse