Their kinship organization is matrilineal. Typically, the Senufo people are studied in three large subgroups that have been relatively isolated. The northern Senufo are called "Supide or Kenedougou", found near Odienne, and who helped found an important kingdom of West Africa and challenged Muslim missionaries and traders. The southern Senufo are the largest group, numbering over 2 million, who allowed Muslim traders to settle within their communities in the 18th century who actively proselytized, and about 20% of the southern Senufo are Muslims. The third group is very small and isolated from both northern and southern Senufo. Some sociologists such as the French scholar Holas mentions fifteen identifiable sub-groups of Senufo people, with thirty dialects and four castes scattered between them.