Why did chinese sea exploration end after the voyages of zheng he

 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.https://answers.yahoo.com/question/index?qid=20130423165801AABEmGv

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