The correct answer to this open question is the following.
Indeed Mansa Musa of the Mali tribe was the richest man of the time no Pharoah had more gold than him. Although he inherited a very rich kingdom, Mansa Musa -as the ruler- took the Mali Empire to the "stratosphere." He knew how to exploit raw materials and natural resources such as gold and salt, which were coveted by all other nations in those years.
Mansa Musa became the Emperor of Mali in 1312. He immediately strengthened commerce and expanded his territory all through the west of Africa. He became so rich and extravagant that when he did his Muslim pilgrimage to Mecca, historians say that he took thousands of people, including servants and soldiers, with him.