Why would a Portuguese Navigator use Chinese maps rather than Portuguese ones? The Portuguese began navigating the world long before 1420.
Makes no sense. Especially when you consider that navigation maps where Top Secrets Eyes Only SPA for nations that had them? Chinese would not just give maps away. Neither would the Portuguese accept a Chinese-made map over their own.
Your theory sounds like something from Wiki, not history.
This is not my theory. Read the book and satisfy yourself about the many kinds of evidence found. Not all records were destroyed by the government, The admiral in charge of the entire expedition of some 800 ships which were then divided into 5 fleets with different areas to explore. Admiral He retired in honor with his own mansion and artfacts. All parts of the world were explored, except Europe which was avoided. The goal was to find new lands to trade with. They went completely around Africa, along the Atlantic and Pacific coast of North and South America, including the Caribbean and Alaska areas. Even Australia. The Portuguese had made progress along Africa’s coast, and there were Portuguese fishing the Grand Banks of Newfoundland, so there may have been maps of those areas, but a map, I think called Piri Reyes, even included Antarctica. I don’t think the Portugues had any maps of Central and South America or the Pacific Ocean sides of those lands. Magellan did not have to discover the Straits of Magellan as the Chinese had mapped then 150 years before his trip and he knew about them.
The evidence is also found in Chinese DNA in various areas where sailers and the concubines brought on the voyage were forced to remain when ships were destroyed in storms. Asain chickens were found in the Americas when the first Europeans arrived. Some of the plants native and exclusive to the Americas were found in China after those dates mentioned. A hole lot of other evidence is supplied. Quite amazing actually. Those shipwrecked waited forever for the rescue that never came as the Chinese turned inward and never followed up on the amazing discoveries made by these 5 fleets