The Sheikhs are Sunni Muslims, widespread in northern and central India as well as Pakistan and all of Bangladesh. Of the four main Muslim groups in South Asia, the Sheikhs rank second, below the Sayyids but above the Pathans and Moguls. While in theory there is no caste hierarchy in Islam, in practice people from these four groups do not usually marry one another, however, in some areas intermarriage may occur, with Sheikhs in particular marrying Sayyids. While the latter groups are "Ashraf" (of foreign, Middle Eastern origin), the Sheikhs are ultimately of local Hindu origin, although their ancestors may have converted to Islam many centuries ago. Sheikhs are engaged in a wide variety of urban and agricultural occupations. Men take the title "Sheikh" or "Mohammed" before their names, and women have "Bibi" after their names.