Published in German, the book focuses on the controversial notion that Western civilization is deeply marked by the influence of the Teutonic peoples. Chamberlain grouped all European peoples—not just Germans, but Celts, Slavs, Greeks, and Latins—into the "Aryan race", a race built on the ancient Proto-Indo-European culture. At the helm of the Aryan race, and, indeed, all races, he saw the Nordic or Teutonic peoples.