The wide distribution of the Satem or Iranian group to the south and west of Asia shows that the Nordics in great numbers conquered the aboriginal inhabitants of these countries and imposed on them the Aryan speech. They invented the caste system to maintain the purity of their blood. In fact, the Hindu word "varna" means both color and caste. In spite of all their efforts, however, the conquering invaders died out almost completely in India and Persia — leaving behind them only their language, and, in some cases, their religion.

The Conquest of a Continent (1933)