What were Timbuktu, Gao, and Djenne?

Answer

Djenne is an ancient town, which was one of the three major cities of the ancient Mali Empire. The other two cities were Timbuktu and Gao. Djenne was a transit point for slaves captured in the interior and sold at slave markets in Gao and Timbuktu. Djenne Djeno is one of the oldest towns in Africa.

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration