There are artifacts and ruins of the ancient Greek, Roman, Persian, Babylonian, Mongol, etc empires, but what remains of the Malian empire? They had no common language, and although coeval with other great empires, there are few architectural remnants. IIRC, the Great Zimbabwe was not Malian.
So just one mega-wealthy ruler and an impoverished people without a culture of their own. Some king he was...
Perhaps he defied the saying, "you can't take it with you".