The idea that peaceful mind could solve all problems in life helped spread Buddhism. It was especially popular in Eastern Asia because there were no dominant regions at the time and it originated in Asia.
If you mean the middle ages the it didn't really grant any freedom. People were kept simple minded and growth was not praised and learning for only for the rich (nobility) and church members. You were considered an outcast if you didn't go to church.
Mansa Musa inherited a kingdom that was already wealthy, but his work in expanding trade made Mali the wealthiest kingdom in Africa. His riches came from mining significant salt and gold deposits in the Mali kingdom. Elephant ivory was another major source of wealth.
