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 Songhai Empire was located in Western Africa south of the Sahara Desert and along the Niger River. At its peak, it stretched well over 1,000 miles from the current modern day country of Niger to the Atlantic Ocean. The capital city of the Songhai was the city of Gao which was located in modern-day Mali on the banks of the Niger River.