Under mandatory musa the empire became

Under Mansa Musa, the West African Mali Empire became expanded, and wealthy, and a center of commerce and learning.

It was under Mansa’s rule that the splendor and riches of Mali were put on display, especially during his pilgrimage to the city of Mecca. Due to the expansive trade of literature in Timbuktu (also spelled Timbuctoo) the Mali Empire became an area where scholars and education flourished.

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explanation: because you need to reduce the pollution on land,the exhaust fumes will stop,and stop it in water,the oil that is in the oceanharms the fish   sorry if you   have been waiting long