 The population of the town of Glogau fell from 33,500 to 5,000, and from 1939 to 1966 the population of Wrocław fell by 25%.Attempts to repopulate Silesia proved unsuccessful in the 1940s and 1950s, and Silesia's population did not reach pre-war levels until the late 1970s.The Polish settlers who repopulated Silesia were partly from the former Polish Eastern Borderlands, which was annexed by the Soviet Union in 1939.