The changes in the number of inhabitants of the city of Lódz between 1939 and 1945 speak for themselves and are an expression of the massacre committed by the Germans. The German authorities established the Lódz Ghetto (Ghetto Litzmannstadt) in the city and populated it with more than 200,000 Jews from the region, who were systematically sent to German extermination camps. It was the second-largest ghetto in occupied Europe, and the last major ghetto to be liquidated, in August 1944. The Polish resistance movement (Zegota) operated in the city and aided the Jewish people throughout its existence. However, only 877 Jews were still alive by 1945. Of the 223,000 Jews in Lódz before the invasion, 10,000 survived the Holocaust in other places. The Germans also created camps for non-Jews, including the Romani people deported from abroad, who were ultimately murdered at Chelmno, as well as a penal forced labour camp, four transit camps for Poles expelled from the city and region, and a racial research camp. Historically, Lódz was multi-ethnic and its diverse population comprised migrants from other regions of Europe. According to the 1931 Polish census, the total population of 604,000 included 375,000 (59%) Poles, 192,000 (32%) Jews and 54,000 (9%) Germans. By 1939, the Jewish minority had grown to well over 200,000.