[geoschmo]

My understanding is that the Chinese hadn't really developed the techniques for deep water (Out of sight of land) navigation. At the time really only the Porteguese had, and later the Spanish and English. The Chinese may have been much stronger militarily, but it would have been extremely difficult to conduct a war by sea against Europe by hugging the coastline around India and Africa. If they had a mind to do it, it would probably have been easier just to march over land like the Mongols did centuries before.