The ancient "Chinese Columbus" map, (I talked about it here) purported to be a 1763 copy of a 1418 original, is being branded as a fake by many historians and map experts.  Antiquities collector Liu Gang said the map proved that Chinese explorer Zheng He discovered and charted the coasts of North and South America over 70 years before Columbus.  The map shows Europe, Africa, Asia, Australia, the Americas, and even Antarctica. 

However, China is not centered on the map, as would be typical of 15th-century Chinese map.  Also, California appears as an island, just like on a certain French map from the 1600s.   Many historians think the "Chinese Columbus" map is a copy of the French one.

Zheng He led the imperial Star Fleet of China on several voyages from 1405 to 1433, but most believe he did not sail to the Americas.