After returning to Italy, Marco Polo wrote a book about his travels. Today’s historians have considerable doubts about this book. Access to Chinese sources allows historians to compare MP to them. There are a lot of divergences. To the degree that some think that the book is a fake or even that MP himself is a fake, too.
On the other hand, there’s stuff in MP’s book that cause historians to wonder, “how did he know that?” Even, “how could he have known that.” He must have been in or near China to have written some of the things that are in that book.
Here’s my theory. While the old boy was writing his book he probably exaggerated. — By a lot. After all, in that day in age who would have been in a position to compare notes with the Chinese?
Here is one scholar’s summary of “The Marco Polo Problem” by Jonathan Dresner: http://dld.bz/fjCqd