Castes are social divisions within one race, not racial divisions

Evidence

As a matter of fact the caste system came into being long after the different races of India had commingled in blood and culture. To hold that distinctions of castes are really distinctions of race, and to treat different castes as though they were so many different races, is a gross perversion of facts. What racial affinity is there between the Brahmin of the Punjab and the Brahmin of Madras? What racial affinity is there between the Untouchable of Bengal and the Untouchable of Madras? What racial difference is there between the Brahmin of the Punjab and the Chamar of the Punjab? What racial difference is there between the Brahmin of Madras and the Pariah of Madras? The Brahmin of the Punjab is racially of the same stock as the Chamar of the Punjab, and the Brahmin of Madras is of the same race as the Pariah of Madras. — Ambedkar, B R, Annihilation of Caste_ The Annotated…, 864