Kea, R.A. 2004. Expansions and Contractions: World-Historical Change And The Western Sudan World-System (1200/1000 B.C. ? 1200/1250 A.D.). Journal of World-Systems Research. 10, 3 (Nov. 2004), 723–816. DOI:https://doi.org/10.5195/jwsr.2004.286.