A expedição de Zheng He em 1433 foi a última e três anos mais tarde um édito imperial baniu a construção de navios de longo curso. Apesar de todo o empreendimento realizado pelo general eunuco muçulmano de etnia hui, a China virou as costas ao mundo. Porquê?
Como seria de esperar não existe apenas um ou dois motivos para que isto tenha acontecido.
Paul Kennedy em "The Rise and Fall of Great Powers" considera que:
(...) There was, to be sure a plausible strategical reason for this decision. The northern frontiers of the empire were again under some pressure from the Mongols and it may have seemed prudent to concentrate military resources in the most vulnerable area. Under such circumstances a large navy was an expensive luxury (...).
a key element in China's retreat was the sheer conservatism of the Confician bureaucracy (...) In this "Restoration" atmosphere , the all important oficialdom was concerned to preserve and recapture the past, not to creat a brighter future based upon overseas expansion and commerce. According to the Confucian code, warfare itself was a deplorable activity (...) Foreign trade by Chinese subjects must have seemed even more dubious to mandarin eyes, simply because it was less under their control.
Paul Kennedy, The Rise and Fall of Great Powers, Vintage Books, New York, 1989, p.7