Mongolian terrain is grassland, so they are nomads and grew up on horseback. Bow and shoot big arrows, and master hands since childhood. Nomads are characterized by herding, hunting and migrating. When these fat grasses are eaten up, they will look for the next weed. Accustomed to climatic conditions. Besides, if winter comes, people sometimes can't eat and have to go out hunting in such bad conditions to support their families. This enables them to cope with bad weather and conditions and survive. It also shows that they are really tough.
Europeans are tall because of their geographical location and meteorological conditions. They developed well, their weapons and swords were not backward, and many warriors emerged. Europeans still have an advantage if they go it alone.
But this war is not a battlefield for one person, but a battlefield for thousands of people in Qian Qian. So Europeans are not dominant in this team battle, they are all weak, just like Mongols holding bows and arrows. Mongols ride horses and shoot arrows every day, and their archery skills are obvious to all. No amount of Europeans can resist such precise archery.
Secondly, Mongols are good at fighting circuitous wars. This trick is often hunting with the Mongols, so we can only deal with him in a roundabout way in the face of fierce beasts. Therefore, Mongolians are handy to use. In the face of European powers, they fought circuitously and in groups. Just right for short Mongols.