During Medieval times, and this is completely over looked, "the Great Kahn" of Mongolia was most likely from all accounts the most powerful man on earth, the only reason he didnt reach France and possibly the shores of Great Britain was because he died of a disease in the process of attacking Europe. His empire was vast and stretched from Japan through India and China up in to the "Principalities of Novgorod" Poland, modern Turkey and the "Holy Roman Empire." The reason he was so good was because his horsemen were very fast in taking out strategic places and crops and nobody could keep up with them. Also one other interesting fact is that you know the South American peoples such as the Aztecs, Mayans etc the only reson they were defeated by the Spanish who were only in very very small numbers is because the Aztecs were fighting to capture and not hurt badly atall so they got massacred and it took a very long while for the Aztecs to cotton on to killing rather than capturing by which time they were almost on their knees. It would have been highly likely that if the Aztecs had killed rather than captured from the start the Spanish would have stood no chance in those jungles and hot wet climates so they would be defeated fairly easily. If the spanish had tried another large attack which is also very unlikely half their ships would have been destroyed on the way to South America by the sea and badly mapped areas of sea and the rest killed in South America by the local peoples.