Did The Chinese Discover America ?

 Menzies, a retired British submarine commander an amateur historian, has written a book, 1421: The Year the Chinese Discovered the World. This book is based on his theory that the Chinese arrived on American shores 71 years before Christopher Colombus. His says that in the first half o t fifteen century China was a naval superpower and he also says that the map European explorer used was made by Chinese.

Then I wonder, what if Menzies is true and the diseases the Europeans brought to America wiped out 90% of the descendants of the Chinese mariners. Maybe we were a mixture between Chinese and Europeans, well the thing is that I can trust his theory, because as Europeans wiped out Chinese' descendant on America they did with natives.