Caste system in Africa
Caste system in Africa varies from one community to the next. Some societies have a markedly developed, rigid caste system between groups of differing origins, whereas others are characterized by a looser relationship between their constituent elements. Countries in Africa that have societies with caste systems within their borders include Mali, Mauritania, Senegal, Gambia, Guinea, Guinea-Bissau, Ivory Coast, Niger, Burkina Faso, Cameroon, Ghana, Liberia, Sierra Leone, Algeria, Nigeria, Chad, Ethiopia, Somalia, Djibouti and Eritrea.
West Africa 
The Osu caste system in Nigeria and southern Cameroon, can be traced back to an indigenous religious belief system, practiced within the Igbo nation. 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 outcaste, 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. They enjoyed protection and privileges but were segregated from ordinary folks. These Osu people married, fraternized and socialized among themselves. The practice continued to this day. An ordinary Igbo person would not marry or permit any of his relations to marry an Osu person. In a few instances where that has happened, every member of that non-Osu who married an Osu became infested and were regarded as Osu. It can be said that the only aspect of Igbo life that keeps the Osu segregation intact is marriage. An Osu could and could only marry a fellow Osu, and no more. It is a taboo and abhorent for an Osu to marry a non-Osu - love or lust being immaterial.
Some suggest the introduction of modernization, the "osu" system is gradually leaving the Igbo land and tradition. Religion has caused the age-old religion to slowly start leaving its traces in the Igbo land. Obinna, in 2012, reports that in Igbo community - especially Enugu, Anambra, Imo, Abia, Ebonyi, Edo and Delta states of the country - Osu caste system remains a social issue. The Osu caste is determined by one's birth into a particular family irrespective of the religion practised by the individual. Once born into Osu caste, this Nigerian person is an outcast, with limited opportunities or acceptance, regardless of his or her ability or merit. Obinna discusses how this caste system-related identity and power is deployed within government, Church and indigenous communities.
Among the Mande societies in Senegal, Gambia, Guinea, Sierra Leone, Liberia, Ivory Coast, and Ghana people are divided by occupation and ethnic ties. The highest hierarchy in the Mande caste system, the Horon (nobles/freeborn), are traditionally farmers, fisherman, warriors and animal breeders, the lowest caste are the Jonow, a "slave" caste, made up of people whose ancestors were enslaved by other Africans during tribal wars. An important feature of this system are castes based on trade, such as blacksmiths and griots.
The Wolof hierarchical caste system in Senegal is divided into three main groups, the Geer (freeborn/nobles), jaam (slaves and slave descendants) and the outcasted neeno (people of caste). In various parts of West Africa, Fula(ni) societies also have caste divisions; in Mali, non-noble/freeborn people (those not technically Fulɓe) are called yimɓe pulaaku (people in the Fula culture).
North Africa 
Class systems in North Africa include the Tuareg social stratification.
Sahrawi-Moorish society in Northwest Africa was traditionally (and still is, to some extent) stratified into several tribal classes, with the Hassane warrior tribes ruling and extracting tribute - horma - from the subservient Znaga tribes. Although lines were blurred by intermarriage and tribal re-affiliation, the Hassane were considered descendants of the Arab Maqil tribe Beni Hassan, and held power over Sanhadja Berber-descended zawiya (religious) and znaga (servant) tribes. The so-called Haratin lower class, largely sedentary oasis-dwelling black people, have been considered natural slaves in Sahrawi-Moorish society.
Horn of Africa 
The caste system found amongst the Borana in the North Eastern Province of Kenya and southern Ethiopia is divided into four distinct castes. At the top, there are Borana Gutu (Pure), followed by Gabbra, then Sakuye, and Watta, a traditional hunter-gatherer caste, being the last. The Watta are condemned to lifelong servitude for members of the higher castes. Among the Tuareg societies found in Burkina Faso, Mali and Niger, exists a similar caste system, where the Bellah slave caste is treated as slaves to other castes.
In Ethiopia, the outcaste groups include the Weyto, who live on the shores of Lake Tana and are despised for eating hippopotamus meat; and the Felasha (or Beta Israel), who made their living from ironworking and pottery until they emigrated to Israel.
East Africa 
In Rwanda, Burundi and eastern Congo it is known as ubuhake. The Tutsi, who comprise about 15% of the population of these areas, were the ruling, cattle-owning caste. Below them were the Hutu, the farmers about 80% of the population. Fewer than 3% of the population are Twa (Pygmies).
During the German suzerainty over Rwanda and Burundi, the authorities reinforced the system by employing Tutsis in hegemonic roles. The Belgian colonialists who succeeded them after World War I continued this policy, instituting 'ethnic' identity cards. After independence, tensions intensified. In 1972, Tutsis were responsible for a wholesale massacre of Hutus. In the 1990s, Hutus responded with counter-massacres.
- Elijah Obinna (2012). "Contesting identity: the Osu caste system among Igbo of Nigeria". African Identities 10 (1): 111–121. doi:10.1080/14725843.2011.614412.
- Fair elections haunted by racial imbalance
- Mauritanian MPs pass slavery law by BBC News
- Oxfam by 'ethnic Africans' it is meant negro
- I. M. Lewis, A pastoral democracy: a study of pastoralism and politics among the Northern Somali of the Horn of Africa, (LIT Verlag Berlin-Hamburg-Münster: 1999), pp.13-14
- The International Dalit Solidarity Network: Caste Discrimination in Africa
- Caste in Africa? by D.M. Todd