The Kingdom of Ghana last form 500 c.e. to 1200 e.c. Ghana was ruled by a power king who controlled the army and had any final say in a matter of justice
camels were first introduced to the shara in about 300 C.E. Camels can drink to about 25 gallens of ater at a time allowing them to go day in the desert without having to stop
The Wangara gold miners knew where gold was plentiful, but even if they were caught and tortured, they would never tell location of the mines
obtaining salt was hard, they either put water into holes and waited for the water to evaporate. Or their where salt mines where there was already salt ready to be harvested
You have to pay 1/6 of an ounce gold for each load of salt. 5/8 of an ounce gold per load of copper and 1 ounce for merchandise Also you have to pay 1/3 of an ounce for each of gold you take out, etc.
These taxes help found their army for protection and also to allow the king to conquer more territories.