It is simply almost nearly impossible.

As I summarized the contemporary sources on Chinggis (Genghis) Khan in Do first hand accounts of Genghis Khan exist?, there are at least two East Asian (Chinese/ Khitan) texts, in addition to very famous Secret History of the Mongols, based on the direct accounts by the persons who met/ served Chinggis in person in his lifetime.

The last nearly contemporary text on Chinggis, Ata-Malik Juvaini (d. 1283 CE)'s History of the World Conqueror (dated to ca. 1260) comes from Persian (Ilkhanate) milieu.

Thus, there are four (nearly) contemporary texts, mutually independent and belonging to different cultural backgrounds (Mongol, Chinese (Jin), Khitan, and Persian), that testify the deed of Chinggis, especially his last expedition to the West since ca. 1219.