What were GAO, Djenne, Timbuktu?

Each city was known for different things:

Gao was and artist paradise. Lot of art work was created here.

Jenne was where a lot of doctors studied. They actually did and operation on the eye and discovered the mosquito disease of malaria.

Timbuktu was a place where a lot of people went to school. People wanted to learn about all different things in SS, Math, Science and literature.