History of the Jews in 20th-century Poland

Following the establishment of the Second Polish Republic after World War I and during the interwar period, the number of Jews in the country grew rapidly. According to the Polish national census of 1921, there were 2,845,364 Jews living in the Second Polish Republic; by late 1938 that number had grown by over 16 percent, to approximately 3,310,000, mainly through migration from Ukraine and the Soviet Russia.

Source: Wikipedia — History of the Jews in 20th-century Poland (CC BY-SA 4.0)