At first glance, the Mongol diplomatic correspondence might seem something quite exotic, and devoid of historical significance. Quite the contrary, explains D. Aigle, who begins by reminding us that many historians, beginning with eighteenth-century Laurent Mosheim or nineteenth-century Abel Rémusat analysed these letters as the remnants of a vast network of exchange and communication from one side of Eurasia to the other. The first important point of the present paper consists of underlining the ability of the Mongol Empire to deal with the various languages of its subjects, partly as a heritage of pre-Mongol Turkic diplomatic practice throughout Eurasia. More precisely, through its ability to recruit and train clerks from diverse origins ― either Buddhists, Muslims or Nestorian, Armenian or Russian Christians, among others ―, Mongol rulers succeeded in adapting diplomatic documents written in their native Mongol language to many other ones. D. Aigle describes from the sources in full detail the process of translation, which could actually imply different transitional languages: for instance from Mongol to Persian and then Latin. Most often, if the original version in Mongolian has been lost, for lack of a real desire to store archive documents, we keep today only the translated version. Besides, if we look closely at the texts, two conclusions arise: first, that the translations were precise and well written, though adapted; and by the way, the Mongol chancery, through all these cultural traders, was able to use Muslim as well as Christian rhetoric, and to convey Mongol ideology through quotations of the Qur’an or of the Bible. The second part of the article deals with the “non-negotiation” attitude of Great Khans at the time of their splendour. Here, the situation was extremely simple: They considered themselves as the conquerors of the world in the name of the divine force, and D. Aigle points to the correspondence between Mongol myths or historic vision and their diplomatic rhetoric. Hence, all the kings of the world were expected to submit. This situation was transformed when Mongol unity broke down. The autonomous power of the Il-Khans of Persia, opposed to Egyptian Mamluks for the control of Syria, needed an ally, obviously the Latin kingdoms engaged in the Crusade movement. However, these negotiations produced very little, not so much because of a basic inability to understand each other, but since the Papacy and the West trusted neither those Nestorian Christians who surrounded the Il-Khans, nor the Il-Khans themselves, who could never forget to make an allusion to their universal power even in their propositions of alliance. At least on this point, Western powers understood only too well what these allusions meant: submission. D. Aigle reviews this topic in a broad study which puts aside many preconceived ideas. She demonstrates that misunderstanding, it this concept is to be used, was not generated by a cultural incapacity of understanding a different culture, but by the confrontation between the global Eurasian vision of the Mongols and the existence of a rival globalisation in the West, a region organised around the idea of Christianity and whose ultimate power, even in matters of transcontinental diplomacy, was Papacy: It was for the Pope to obtain the conversion of all the peoples of the world.