I think it is absolutely amazing that someone at that time could have traveled that far.  I wrote about the Letters from Mexico by Hernan Cortes and found that a lot of scholars doubted truth in his work too.  I wonder why people chose to doubt what these men wrote?  I find it really interesting, whether or not he saw the Great Wall of China or not his whole piece shouldn't be questioned.  I think people should come with the attitude of what can I learn from this piece.  What do you think?