Caste system among South Asian Muslims

Muslim communities in South Asia have a system of social stratification arising from concepts other than "pure" and "impure", which are integral to the caste system in India. It developed as a result of relations among foreign conquerors, local upper-caste Hindus convert to Islam (ashraf, also known as tabqa-i ashrafiyya) and local lower-caste converts (ajlaf), as well as the continuation of the Indian caste system by converts.

Source: Wikipedia — Caste system among South Asian Muslims (CC BY-SA 4.0)