 Their subjugation regardless of their religion was sometimes ideologically justified by nobles and some Islamic scholars, even though some scholars took a more nuanced view that Muslims can only enslave non-Muslims and they should not enslave other Muslims, states Hamel – a professor of History specializing in African Studies.They along with "Swasin" in Morocco and other northern fringe societies of the Sahara, were a part of a social hierarchy that included the upper strata of nobles, religious specialists and literati, followed by freemen, nomadic pastoral strata and slaves.The Haratin were hierarchically higher than the "`Abid" (descendant of slaves) at the very bottom, but lower than "Ahrar".