The master race (German: Herrenrasse, Herrenvolk) was first used by the British colonial power to denote the original inhabitants of the areas (colonies) that they had conquered and ruled. It derives from nineteenth century racial theory, which posited a hierarchy of races placing African Bushmen and Australian Aborigines at the bottom of the hierarchy while white Europeans were at the top. This concept is similar to the American White supremacy movement.
Later it became a concept in Nazi ideology, which holds that the Germanic and "Nordic" people represent an ideal and 'pure' race. The originator of the Nazi version of the theory of the master race was Count Arthur de Gobineau, who argued that cultures degenerate when distinct "races" mix. It was widely believed at this time that southern European peoples were racially mixed with non-Europeans from across the Mediterranean, while Northern Europeans remained "pure". Hence in Nazism the racial ideal was the blond blue-eyed Nordic individual. The term "Aryan race" was commonly used to name this ideal. The imagined superiority of these people supposedly made them born leaders, or a "master race". Other authors to fuel this thought included Guido von List (and his follower Lanz von Liebenfels) and British Houston Stewart Chamberlain who all thought that the Germanic race was superior to others, and that given the purification of the German people from the races who were "polluting" it, a new Millenarian age of Aryan God men would arrive.
The term Aryan derives from the ancient peoples who occupied Iran and the Indus Valley. Following the ideas of Gobineau and others, the Nazi theorist Alfred Rosenberg claimed that these were a dynamic warrior people who originated in northern climes, from which they migrated south, eventually reaching India. They were supposed to be the ancestors of the ancient Germanic tribes, who shared their warrior values. Following Nietzsche (but distorting him), Rosenberg claimed that Christianity was an alien Semitic slave-morality inappropriate to the warrior Aryan master-race.
In Nazi Germany, marriage of an "Aryan" with a non-Aryan was forbidden. To maintain the purity of the Nordic master-race eugenics was practised. In order to eliminate "defective" citizens, the T-4 Euthanasia Program was administered by Karl Brandt to rid the country of the mentally retarded or those born with genetic deficiencies.
Modern geneticists no longer give credence to the biological arguments on which the hierarchical model of race is built.