Maps showing the distribution of German-speaking peoples in Europe had circulated since the nineteenth century, but advances in printing technology in the 1920s enabled them to do so even more widely. These maps took on more explicitly revisionist geopolitical agendas after the First World War as a reaction to Germany’s territorial losses and a reflection of the growing influence of geographers who engaged in Volks- und Kulturbodenforschung (research into the rootedness of ethnic and cultural groups in particular spaces). Institutions such as the Deutsche Akademie, founded in 1925, and the Stiftung für deutsche Volks- und Kulturbodenforschung, founded in 1926, propagated the notion that central Europe was an inherently German space. Maps such as this one promoted the idea that Germany’s “natural borders” extended beyond the official ones that the Treaty of Versailles had drawn, and they cultivated a yearning for territorial revision and “Lebensraum” (living space) on which the Nazi Party soon capitalized.

The author of this particular map, the geographer Albrecht Penck, had established a reputation prior to the First World War as one of the world’s leading researchers in climatology, glaciation, and the study more broadly of how physical features manifest the underlying geological conditions. During and after the war, however, Penck grew increasingly interested in studying Germany’s ethnic and cultural presence throughout central Europe. His ideas attracted conservative nationalists and, later, National Socialists, who drew on Penck’s writings to justify their own calls for Germany’s territorial expansion throughout central Europe.

The 1925 book in which Penck’s map and accompanying article appeared was edited by the ethnologist Karl Christian von Loesch, a founding member in 1922 of the Deutscher Schutzbund für das Grenz- und Auslandsdeutschtum [the German Protective League for Germandom in the Borderlands and Abroad]. The League made sure that the preservation of the rights and livelihoods of Germans throughout central and eastern Europe remained a priority for the German government. Longer term, it nurtured the public’s long-term desire to annex the lands where these Germans lived, and this map clearly served that function. Loesch’s own article in this 1925 book promoted his concept of “Umvolkung,” which expressed both the fear that German communities abroad were being de-Germanized by their respective postwar states—such as Poland or Czechoslovakia, for instance— and the potential for programs and policies to maintain and even to re-Germanize those same communities. During the Weimar Republic, the maintenance effort took the form of diplomatic negotiations and financial subsidies, but, under the Nazi regime, the concept of “Umvolkung” would guide the regime’s agenda of military conquest and forced resettlements throughout the east.