The Sahelian kingdoms were a series of kingdoms or empires that were centered on the sahel, the area of grasslands south of the Sahara. The wealth of the states came from controlling the trade routes across the desert. Their power came from having large pack animals like camels and horses that were fast enough to keep a large empire under central control and were also useful in battle. All of these empires were also quite decentralized with member cities having a great deal of autonomy.