The caste system is a social hierarchy based on ones birth that is tied to concepts of purity and social status. It has existed in some form in India for at least 3,000 years. The caste system divides Hindus into four main categories: Brahmins, Kshatriyas, Vaishyas, and Shudras, with each group occupying a specific place in the complex hierarchy. The main castes were further divided into about 3,000 castes and 25,000 sub-castes, each based on their specific occupation. Outside of this Hindu caste system were the achhoots - the Dalits or the untouchables. The system bestows many privileges on the upper castes while sanctioning repression of the lower castes by privileged groups. The Indian Constitution has outlawed the practice of Untouchability and the Indian Government has established special quotas in schools and Parliament to aid the lowest castes. However, caste discrimination is not permitted in gaining employment and access to educational and other opportunities. The caste system as it exists today is thought to be the result of developments during the collapse of the Mughal era and the rise of the British colonial government in India. The British Raj furthered this development, making rigid caste organization a central mechanism of administration.