East after the 7th century, followed by a slavery system that targeted the pagans. According to Susan McIntosh – a professor of Anthropology specializing in African societies, archeological evidence shows that Arabs and Berbers had expanded and established an integrated sub-Saharan trade and transport network with West Africa, building upon the pre-existing trade routes through Western Sudan. This trade by 9th to 10th centuries, states McIntosh, included commodities and slaves. The reach of slave trading had extended into Ghana and the western Atlantic coast by the 11th century, and the slave raiding, capture, holding and trading systems became increasingly sophisticated in 13th and 14th century Mali Empire and 16th century Songhai Empire. As the practice of slavery grew, so did the caste system. Tamari suggests that a corollary of the rising slavery system was the development and growth of the caste system among numerous ethnic groups of Africa by about the 13th century. McIntosh concurs with Tamari's reasoning approach, but disagrees with the dating. McIntosh states that the emergence of caste systems likely occurred much earlier in the West African societies such as Soninke, Mande, Malinke, Wolof, and others. She places the development and spread of castes in these societies to about the 10th century, because the slave capture, slave trade and slave holding by elite families was an established institution in West Africa by then, and slavery created a template for servile relationships and social stratification of human beings. The linguistic evidence suggests that stratification structure and words relating to caste system and slavery likely were shared between the many ethnic groups, and possibly some others such as the Dogon people of West Africa. However, the linguistic differences between the caste and slave systems between Soninke and northern ethnic groups of Africa such as the Tuareg people and Moors suggests that these evolved separately. Comparison between castes of Africa and South Asia Louis Dumont, the 20th-century author famous for his classic Homo Hierarchicus'', recognized the social stratification among the ethnic groups in West Africa, but suggested that sociologists should invent a new term for West African social stratification system. Other scholars consider this a bias and isolationist because the West African system shares all elements in Dumont's system, including economic, ritual, spiritual, endogamous, elements of pollution, segregative and spread over a large region. According to Anne Haour – a professor of African Studies, some scholars consider the historic caste-like