In 1939, during the Polish September Campaign, the Nazis occupied Krakow, Poland, a thriving Jewish community of 70,000 Jews. Jews were consigned to forced labor, and all Jews were required to wear identifying armbands. Synagogues were ordered closed and all their valuables turned over to Nazi authorities. In May 1940, the Nazis ordered a massive deportation of Jews from the city, leaving only 15,000 behind in Krakow's Jewish ghetto, crammed into 3,000 rooms. German businessman Oskar Schindler came to Krakow to take advantage of the ghetto labor, and subsequently worked furiously to save Jews, as portrayed in the film, Schindler's List. In March 1943, the Nazis carried out the final 'liquidation' of the ghetto.