Why did the sudanic states develop in the sahel and what advantages did they have?

Sahel is considered as a point of interchange between the forests of the South and North Africa. Along the coast, several Sudanic states were established between the trading cities, it only indicates that the state was subjected to be suffering from outbreak and periodic scarcities. The advantage of the system is it supported the authority of the rulers.

bujías y una hora antes y no me parece muy difícil