By the nineteenth century, throughout the West there was a general consensus that the human population of the world could be divided into a small number of what were called ‘races’. Although there was not absolutely uniform agreement on how many and which groups were races in this sense, JF Blumenbach's division into five – Malayan; Ethiopian (sub-Saharan African, or black); American (indigenous peoples of the Americas); Caucasians (white, or of European ancestry); and Mongoloid (East/Southeast Asian) – can serve as a rough consensus. Because of controversy over the term ‘race’, I will provisionally refer to such groups in the more neutral terminology of ‘classic racial groups’.

Classic racial groups were thought to possess the following characteristics, which were implied in calling them ‘races’:

Note that the fifth feature means that classic racial groups were not defined by phenotypic characteristics. The Nazis did not define what they regarded as racial groups by phenotype, which leads us to a second strand of racial theory that was rather different from Blumenbach's. Nazism drew on a prominent alternative strand in European racial thought in which races were thought of as national (French, German, Italian) rather than continental.