is the bigger differentiation in life expectancy in modern India. Influence on other religions While identified with Hinduism, caste systems are found in other religions on the Indian subcontinent, including other religions such as Buddhists, Christians and Muslims. Muslims Caste system has been observed among Muslims in India. They practice endogamy, hypergamy, hereditary occupations, avoid social mixing and have been stratified. There is some controversy if these characteristics make them social groups or castes of Islam. Some scholarls assert that the Muslim castes are not as acute in their discrimination as those of the Hindus, while critics assert that the discrimination in South Asian Muslim society is worse. From the earliest days of Islam's arrival in South Asia, Arab, Persian and Afghan Muslims have been recognised as an upper caste. Some upper caste Hindus who converted to Islam became part of the governing groups, who along with these foreign groups came to be known as Ashrafs (or nobles). Below them are the middle caste Muslims called Ajlafs, and the lowest status Muslims of the Arzals. Anti-caste activists like Ambedkar called the Arzal caste among Muslims as the equivalent of Hindu untouchables, as did the British ethnographer Herbert Hope Risley. In Bengal, some Muslims refer to the social stratification within their society as qaum (or Quoms), a term that is found among Muslims elsewhere in India, as well as in Pakistan and Afghanistan. Qaums have patrilineal heredity, with ranked occupations and endogamy. Membership in a qaum is inherited by birth. Barth identifies the origin of the stratification from the historical segregation between pak (pure) and paleed (impure)—defined by the family's social or religious status, occupation and involvement in sexual crimes. There is history of skin color defining Pak/Paleed, but that does not have historical roots, and was adopted by outsiders through analogy with the Hindu Caste system. Similarly, Christians in Pakistan are called "Isai", meaning followers of Isa (Jesus). But the term originates from Hindu Caste system and refers to the demeaning jobs performed by Christians in Pakistan out of poverty. Efforts are being made to replace the term with "Masihi" (Messiah-followers), which is preferred by the Christians citizens of Pakistan. Endogamy is very common in Muslims in the form of arranged consanguineous marriages among Muslims in India and Pakistan. Malik states that the lack of religious sanction makes qaum a "quasi-caste", and something that is found in Islam outside South