caste system. The Fula caste system has been fairly rigid and has medieval roots. It was well established by the 15th century, and it has survived into modern age. The four major castes, states Martin Kich, in their order of status are "nobility, traders, tradesmen (such as blacksmiths) and descendants of slaves". According to the African Commission on Human and Peoples' Rights, the Fulani people have held on to "a strict caste system". The upper caste consists of the nobles. Below these are the marabouts or clerics, then the cattle owning Fula people. Below all these are the artisan castes, which includes the blacksmiths, potters, griots, genealogists, woodworkers, and dressmakers. They belong to castes but are not enslaved and are free people. Then there are those castes of captive, slave or serf ancestry: the Maccuɗo, Rimmayɓe, Dimaajo, and less often Ɓaleeɓe, the Fulani equivalent of the Tuareg Ikelan known as Bouzou (Buzu)/Bella in the Hausa and Songhay languages respectively. The Fulani castes are endogamous in nature, meaning individuals marry only within their caste. This caste system, however, wasn't as elaborate in places like northern Nigeria, Eastern Niger or Cameroon. According to some estimates, by the late 19th century, slaves constituted about 50% of the population of the Fulɓe-ruled Adamawa Emirate, where they were referred to as jeyaɓe (singular jeyado). Though very high, these figures are representative of many other emirates of the Sokoto Caliphate, of which Adamawa formed a part. The castes-based social stratification among the Fula people was widespread and seen across the Sahel, such as Burkina Faso, Niger, Senegal, Guinea, Mali,Jean Gallais (1962), Signification du groupe ethnique au Mali, L'Homme, T. 2, No. 2 (May - Aug., 1962), pages 106-129 Nigeria, Sudan, and others. Igbo people The Osu caste system in Nigeria and southern Cameroon of the Igbo people can be traced back to Odinani, the traditional Igbo religion. It is the belief of many Igbo traditionalists that the Osus are people historically owned by deities, and are therefore considered to be a 'living sacrifice', an outcast, untouchable and sub-human (similar to the Roman practice of homo sacer). This system received literary attention when it became a key plot point in No Longer at Ease by Chinua Achebe. People regarded as modern-day Osu in Igboland are descendants of individuals who volunteered and were sacrificed to the various gods. These fore-fathers pledged themselves and their descendants to these gods.