What is it you need exactly?
<span>1.The Chinese did not have any more uses for a navy.
2.The voyages were becoming to expensive.
3.They wanted to divert their attention to stopping the Mongolians.
4.The Chinese began to adopt a policy of isolationism and did not want to interact with anyone.</span>https://answers.yahoo.com/question/index?qid=20130423165801AABEmGv
The Arab traders who traded in Africa were responsible for bring Islam to Africa