there might be documented building structures and such of thier landing, however there we're maps shown and discussed on discovery on thier "Search for Atlantis" program ... documenting that several older nations from the meds had trade routes setup, this was then again used again in another documentary about nortical navigation.
Quote: "Oh and indi, please do not make the mistake of thinking Americans deliberately are trying to hide the previous presence of and white peoples massacres of Native Americans under the rug. That is just rediculous. "
certainly isn't ... hell even disney has covered it - maybe in a cutsie mannor but still there.
... as i said, the land is already there you technically can't discover it for everyone - you discover it for your own people.
Tommorrow some Chinese Scientist dude might discover cold fusion (god knows what he'd do with it) ... but if he never shared it with the rest of the world and 30years later some american scientist discovered it, they would claim they discovered it first.
If you waited another 25-30years and then released the documents that proved the Chinese were the first, it wouldn't change history.
And you could bitch about it all you want - in the eyes of the americans they'd be the first. History lessons might be ammended with the Chinese doing it as a tid-bit but essentially nothing would change, and most people apart from the Chinese would even care who discovered it just that we can all use it.