Answer:
The Hausa states were exhausted economically because of internal and external constant wars. It was taken over by the Kanem-Bornu after the conquest of Usuman dan Fodio.
The location of Kanem-Bornu was at the center of African continent which is now part of Chad and Nigeria. The special geopolitical position attracted trades and the empire actually lied on the famous trans-Saharan trade route, that contributed to its power.
Step-by-step explanation: