term Bidan is a "caste synecdoche" that refers to Hassani (warrior) and Zwaya (clerical) clans. In the slave castes, they recognized two layers, the `Abid (slaves) and Haratins (freed slaves). According to Remco Ensel – a professor of Anthropology specializing in Maghreb studies, the word "Haratin" in Moroccan is a pejorative that connotes "subordination, disrepute" and in contemporary literature, it is often replaced with "Drawi", "Drawa", "Sahrawi", "Sahrawa" or other regional terms. The Haratins historically lived segregated from the main society, in a rural isolation. 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. This hierarchy, states Ensel, has been variously described as ethnic groups, estates, quasi-castes, castes or classes. Tuareg people The Tuareg people are a large Berber ethnic confederation found in North Africa. They principally inhabit the Sahara desert, in a vast area stretching from far southwestern Libya to southern Algeria, Niger, Mali and Burkina Faso. Traditionally nomadic pastoralists, small groups of Tuareg are also found in northern Nigeria. Tuareg society has traditionally featured clan membership, social status and caste hierarchies within each political confederation. These hierarchical systems have included nobles, clerics, craftsmen and unfree strata of people. In Tuareg hierarchical caste system, the nobles constitute the highest caste. They are known in the Tuareg language as imúšaɣ (Imajaghan, "the proud and free" in the amazigh language). The nobles had a monopoly on carrying arms and camels, were the warriors of the Tuareg regions. They may have achieved their social status by subjugating other Tuareg castes, keeping arms to defend their properties and vassals. They have also collected tribute from their vassals. This warrior nobility has traditionally married within their caste, not to individuals in strata below their own. A collection of tribes, each led by a noble, forms a confederation called amanokal, whose chieftain is elected from among