Why did most extermination camps take place in Poland?

Initially – before mid-1941, the start of the war against Russia – the Nazi bosses (leaders) wanted to get rid of the Jews but not necessarily exterminate them. They put them in ghettos far away from Germany because the population had already indicated that they were not served by all that brutal violence under their noses. Poland, which had already been conquered in 1939 and divided with the Soviet Union, offered that opportunity. The intention was once to transfer those Jews to inhospitable areas. With the invasion of the Soviet Union in June 1941, the Einsatzgruppe (special killing brigades that murdered communists and Jews in the wake of the regular army) took a much more drastic approach and two extermination camps were established in Poland in 1941: Chelmno and Belzec. Later the others joined: Trebliknka, Sobibor, Majdanek (part concentration camp), Auschwitz-I, Auschwitz-II (Birkenau): far from the bedside of German and other civilians who, although they heard rumors, could always look away, pretend their noses was bleeding.