Conventional price elasticity of demand is a simplistic and elementary formula that has mathematical and economic deficiencies when applied to price (rates) and demand (balances) of deposit products: It does not recognize inverse relations between price and demand.
At its peak in 1300, the Mali Empire covered an area about twice the size of modern-day France and stretched to the west coast of Africa. In the late 19th century, during the Scramble for Africa, France seized control of Mali, making it a part of French Sudan.
The Mali Empire was also a world-famous intellectual center. It housed the University of Timbuktu - one of the oldest universities in the world. After reaching its height under the leadership of Mansa Musa, Mali gradually declined in the 15th century. The Rise and Rule of the Songhai Empire. Songhai began with the river city of Gao. Inhabitants of the city expanded their control to the area of the Niger River bend during the 9th century C.E. The state of Songhai was incorporated under the Mali Empire in the 14th century, but reasserted its independence as Mali weakened in the 15th century. Armed with war canoes and a cavalry, Sonni Ali led successful military campaigns that expanded Songhai's borders to include the cities of Timbuktu (1468) and Jenne (1473).