Note: Do not rely on this information. It is very old.
Sudras
Sudras, the fourth caste of the Hindu social system but the word has an ethnical value, because the Sudras were the Mongoloid aborigines, who after the Aryan conquest of North India preserved their personal freedom by adopting the Brahminical religion, language, and general culture; are everywhere now intermingled, especially with the Vaisyas or third Aryan caste.