 The six camps considered to be purely for extermination were Chelmno extermination camp, Belzec extermination camp, Sobibor extermination camp, Treblinka extermination camp, Majdanek extermination camp and Auschwitz extermination camp (also called Auschwitz-Birkenau).Whereas the Auschwitz II (Auschwitz–Birkenau) and Majdanek camps were parts of a labor camp complex, the Chełmno and Operation Reinhard death camps (that is, Bełżec, Sobibór, and Treblinka) were built exclusively for the rapid extermination of entire communities of people (primarily Jews) within hours of their arrival.All were constructed near branch lines that linked to the Polish railway system, with staff members transferring between locations.