Last year, in a book entitled Origin of the Olmec Civilization, Professor Mike Xu, a Chinese who teaches in the foreign languages department at the University of Central Oklahoma, proposed a hypothesis which aroused a storm of controversy in archeological circles. In Xu's view, the first complex culture in Mesoamerica may have come into existence with the help of a group of Chinese who fled across the seas as refugees at the end of the Shang dynasty. The Olmec civilization arose around 1200 BC, which coincides with the time when King Wu of Zhou attacked and defeated King Zhou, the last Shang ruler, bringing his dynasty to a close.
Furthermore, Xu had "explosive" evidence in the form of the written word. Over the past three years he has found some 150 glyphs on photographs of and real specimens of Olmec pottery, jade artifacts and sculptures. As well as himself leafing through dictionaries of ancient Chinese, he has also taken his drawings of these markings to be examined by mainland Chinese experts in ancient writing, and most have agreed that they closely resemble the characters used in Chinese oracle bone writings and bronze inscriptions.
That's a lot more recent. Sailed the big ocean? In what? The Bering Strait would be wild and impassable by any primitive craft.
That's the reason I look at any theory made on ancient China by modern Chinese -- they're too close to the Action. A true historian should be removed from his/her point of study -- I'd prefer a Chinese archaeologist studying the wonders of Abbasid Baghdad, for example.