The German Nazi Party adopted and developed several racial hierarchical categorizations as an important part of its racist ideology (Nazism) in order to justify enslavement, extermination, ethnic persecution and other atrocities against ethnicities which it deemed genetically or culturally inferior. The Aryan race is a pseudoscientific concept that emerged in the late-19th century to describe people who descend from the Proto-Indo-Europeans as a racial grouping and it was accepted by Nazi thinkers. The Nazis considered the putative "Aryan race" a superior "master race" with Germanic peoples as representative of the Nordic race being the best branch, and they considered Jews, mixed-race people, Slavs, Romani, black people, and certain other ethnicities racially inferior subhumans, whose members were only suitable for slave labor and extermination. In these ethnicities, Jews were considered the most inferior. However, the Nazis considered Germanic peoples such as Germans to be significantly mixed between different races, with the East Baltic race being considered inferior by the Nazis, and that their citizens needed to be completely Nordicized after the war. The Nazis also considered some non-Germanic groups such as Sorbs, Northern Italians, and Greeks to be of Germanic and Nordic origin. Some non-Aryan ethnic groups such as the Japanese were considered to be partly superior, while some Indo-Europeans such as Slavs, Romani, and Indo-Aryans were considered inferior.

These beliefs stemmed from a mixture of historical race concepts, 19th-century and early 20th century anthropology, 19th-century and early 20th-century biology, racial biology, white supremacism, notions of Aryan racial superiority, Nordicism, social Darwinism, German nationalism, and antisemitism with the selection of the most extreme parts. They also originated from German military alliance needs. The term Aryan generally originated during the discourses about the use of the term Volk (the people constitute a lineage group whose members share a territory, a language, and a culture). Unlike the German armed forces (Wehrmacht) only used for military conflicts, the Schutzstaffel (SS) was a paramilitary organization directly controlled by the Nazis with absolute compliance with Nazi racial ideology and policies.

The Adolf Hitler-led Nazis claimed to observe a strict and scientific hierarchy of the human race. Hitler's views on race and people are found throughout his autobiographical manifesto Mein Kampf but more specifically, they are found in chapter 11, the title of which is "Nation and Race". The standard-issue propaganda text which was issued to members of the Hitler Youth contained a chapter on "The German Races" that heavily cited the works of Hans F. K. Günther. The text seems to categorize the European races in descending orders in the Nazi racial hierarchy: the Nordic (including the Phalic sub-race, a subgroup of the Nordic race), Mediterranean, Dinaric, Alpine, and East Baltic races. In 1937, Hitler spoke in the Reichstag and declared, "I speak prophetically. Just as the discovery that the earth moved around the sun led to a complete transformation of the way people looked at the world, so too the blood and racial teachings of National Socialism will change our understanding of mankind's past and its future."

In his speeches and writings, Hitler referred to the supposed existence of an Aryan race, a race that he believed founded a superior type of humanity. According to Nazi ideology, the purest stock of Aryans were the Nordic people of Germany, England, the Netherlands, and Scandinavia. The Nazis defined Nordics as being identified by their tall stature (average 175 cm [5 ft 9 in]), their long faces, their prominent chins, their narrow and straight or aquiline noses with a high base, their lean builds, their dolichocephalic skulls, their straight and light hair, their light eyes, and their fair skin. The Nazis regarded the Germans as well as the English, Danes, Norwegians, and Swedes as the most racially pure in Europe. Indeed, members of the Schutzstaffel (SS) considered Aryans not to be of a single ethnic group, and did not have to be exclusively German, but instead could be selected from populations across Europe to create the "master race". The normative German term for them was that there existed an arisches Volk (Aryan people), not arische Rasse (Aryan race).

The Nazis believed that the Germanic peoples of Northwestern Europe belonged to a racially superior Nordic subset of the larger Aryan race, who were regarded as the only true culture-bearers in civilized society. 'Aryan' world history became the link between East and West, also between the Old World and New World. The principal dogma, in this Nazi historiography, was that the glories of all human civilizations were creations of the 'Aryan' master race, a culture-bearing race.^{[page needed]} The Nordic (Germanic) Aryans did not develop into great civilizations in ancient history because they lived in the cold, damp, and harsh environment for a long time. However, they kept their purity intact and later only the Germanic Aryans at the end of history would eventually conquer and dominate the world because of their purity was maintained, being proved during the Germanic domain of Industrial Revolution (the Slavs later mixed with Asiatic peoples during the Middle Ages and lost their racial purity and superior talent).^{[page needed]}

The Nazis claimed that the Germanic peoples specifically represented a southern branch of the Aryan-Nordic population. The Nazis considered that the Nordic race was the most prominent race of the German people, but that there were other sub-races that were commonly found amongst the German people such as the Alpine race population who were identified by, among other features, their lower stature, their stocky builds, their flatter noses, and their higher incidences of darker hair and eyes. Hitler and the Nazi racial theorist Hans F. K. Günther framed this as an issue which would be corrected through the selective breeding of "Nordic" traits. In general terms, Günther diagnosed combinations of the following elements in the German Volk: Nordic (nordisch); Mediterranean (westisch, mediterran, mittelländisch); Dinaric (dinarisch); Alpine (ostisch, alpin); East Baltic (ostbaltisch); Phalian (fälisch, dalisch). These theories generated some fear in southern Germans, as they thought that Nazism was a form of "Nordic colonialism" and that non-Nordics would be treated as second-class citizens.

Nonetheless, Hitler stated "the principal ingredient of our people is the Nordic race (55%). That is not to say that half our people are pure Nordics. All of the aforementioned races appear in mixtures in all parts of our fatherland. The circumstance, however, that the great part of our people is of Nordic descent justifies us taking a Nordic standpoint when evaluating our character and spirit, bodily structure, and physical beauty." Nazis were also tolerant of native Germans who did not possess the physical appearance of the Nordic race as long as they shared the traits of being a "German" which were "courage, loyalty and honor".

In the 1920s, the Reichsführer-SS Heinrich Himmler came under the influence of Richard Walther Darré, who was a leading proponent of the blood and soil concept. Darré strongly believed that the Nordic race was racially superior to all other races and he also strongly believed that the German peasants would play a fundamental role in securing Germany's future and Germany's future expansion in Eastern Europe, and in the racial strength of the German people.