The answer is:
Aryan racial theories and policies of Hitler.
Hitler believed that an Aryan race was a common origin for all German peoples. This race was meant to have supremacy and a pure bloodline that was meant to have originated on the East and came to settle in most of Europe. The Aryan race was an anthropological theory that Hitler strongly believed among other Nazi ideologists used to expose allegedly inferior cultures, where Jews became the main target, among Gypsies, Poles and Slavic peoples.
The Nazi regime went far in issuing a "Certificate of German Blood" that was used to deny or allow German citizenship, based on checking on Jewish origins. The discrimination and denial of human rights to Jewish and other minorities came to a "final solution" were basically a systematic plan for exterminating occurred. The concentration camps were a means of mass murder and slavery work.