Regarding the bogus bit, may I suggest reading a book titled 1421, authored by Gavin Menzes.
Based on what I've seen of it, that book consists largely of fanciful speculation. It's a well-established fact that Chinese seafarers reached East Africa and entirely possible that they explored other locations. But the climate record does not support any possible circumnavigation of Greenland in any craft not specially outfitted for icebound polar navigation circa 1421. No evidence exists to suggest that the Chinese possessed such equipment. Even reaching Greenland in those days (without meteorological satellite data or modern telecommunications) would make one quite lucky. Superior Chinese shipbuilding technology, however, probably would allow their fleet to weather some nasty storms, but even the Titanic couldn't survive an iceberg.