*= Edit
I've heard of this book a couple of years ago, but never really gave it much thought until I started thinking of making a Bao Chuan (treasure ship) in Lego. So I started doing more research and then I hit upon the website http://www.1421.tv/news.asp
I decided to have a look and even bought the book "1421 When China Discovered America", with the most compelling evidence I've heard were of those maps that European explorers later on had *used* to get to those particular places and claim to have "discovered" them.
*There's also a followup book called, "When China Discovered the World"... basically, they supposed to have went around the world.
I always wondered about who was it that charted and mapped "undiscovered" places long before they were apparently "discovered". Ever since I was still in my preteens learning about Europe's voyages of discovery and reading things like that.
*Its also interesting to note that Admiral Zheng He's nickname was "3 Jewels" or "Sin Bao" in Chinese. Funny how similar that name is to Sinbad, a legendary muslim sailor & explorer who went on voyages and adventures around the world.