Marco Polo's book — The Travels, The Description of the World, II Milione, or whatever we prefer to call it — is unquestionably the best known of all contemporary sources on that unprecedented historical phenomenon, the Mongol Empire of the thirteenth and fourteenth centuries. That is not to say that it is by any means the best source.
As history, it cannot compare, for example, with Rashīd al-Dīn's Jāmi' al-tawārīkh, and as a European travel account (if that is what it is), it is not remotely in the same class as Friar William of Rubruck's Itinerarium. Nevertheless, while Friar William may have been completely forgotten and Chinggis Khan remembered only as someone a political reactionary can, by dint of great effort, get himself (or herself, one should hasten to add) to the right of, there are many who know at least something about Marco Polo: perhaps principally the fact that he went to China — as almost everyone has hitherto supposed that he did.