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.