Before Yuan Shizu Kublai Khan came to the throne, the Great Mongolian country had carried out three large-scale western expeditions, namely, the expedition initiated by Genghis Khan in the 1320s to Central Asia, Iran, the North Caucasus and the Volga Valley War; 1330s —In the Yuan Taizong Dynasty in the 1940s, the expeditions to the Eurasian steppe and Eastern Europe led by the kings Batu; and in the 1350s, after the emperor Xianzong Mengge ascended the throne, the Mongolian army led by Xu Liewu eliminated the Arab Abbasids The military operations of the dynasty (that is, the “big food in black” in our historical records). Among them, the second western expedition in Mongolia and Yuan Dynasty in my country is often referred to as “the western expedition of Batu” or “the eldest son of the western expedition”. Then, apart from the final decision that the Mongolian kings, concubines and nobles all participated in the expedition with their eldest sons and their subordinate populations, what was the background of the Mongolian expedition? What other issues were discussed in the decision-making of the western expedition? This is the content that this article hopes to explore .