The document summarizes the caste system of ancient India, which divided Indian society into five hierarchical social groups based on occupation. The Aryan invaders established this system, with the Brahmins as priests and teachers at the top, followed by the Kshatriyas as warriors, Vaishyas as traders and merchants, Sudras as servants, and Harijans as untouchables at the bottom. People were born into their caste and it determined their occupation, who they could interact with, and their status in society.