Reply #3: Well, I'm *assuming* you already know about "1421"...

[eppur_se_muova]

One of the works cited in that book is "When China Ruled the Seas" by Levathes. Very interesting reading, if you have trouble seeing how a Chinese discovery of America is plausible. I actually read this back in the 90's, long before "1421" was published, so I was 'softened up' for "1421" and found it much easier to read as a result.

http://www.amazon.com/When-China-Ruled-Seas-1405-1433/d...

You might also enjoy "Voyage of the Brendan" and "The Voyage of the Matthew: John Cabot and the Discovery of America". Some of the background to Basque claims is in Kurlansky's "A Basque History of the World", but kind of scant, since written records apparently were suppressed.