So I just bought the second book by Gavin Menzies, having read his previous book 1421 the year China discovered America. Great read, and if true I think would rewrite history. That is if scholars would allow it.
But I wonder, you think Mayans, etc would mention something about huge treasure ships of their coasts etc. And the stones or monuments that the Chinese supposedly left could be dated, or at least better described. Also he described the fleets, several of them to be in the hundreds, that traveled the world at the same time, some would have sunk, only three are listed on his site and they are potential. Most credible claims are off the coast of China. But it should be a great read nonetheless, and if someday it turns out to be true, then awesome.