The predecessor of the Mongol Empire was the Yuan Dynasty, which was able to be established and was closely related to Genghis Khan's conquests. It is undeniable that Genghis Khan's conquest laid the foundation for Kublai Khan to establish the Yuan Dynasty. After the establishment of the Yuan Dynasty, Genghis Khan was revered as the first emperor of the Yuan Dynasty, and at the same time was posthumously named The Shengwu Emperor, so Genghis Khan's merits are indelible.
From the beginning of the Mongol Empire, Genghis Khan formed the Mongol cavalry, and at that time, the Mongol cavalry was invincible. After Genghis Khan unified the steppe tribes, in 1211 AD, Genghis Khan began a large-scale expansion of the Mongolian Iron Horse, and since then, the number of Mongolian Iron Horsemen has continued to grow, and finally defeated the Song Dynasty.

After the expansion of the Mongol Iron Horse, in just five years, the Mongolian Iron Horse occupied Jin and Goryeo. As a result, the combat effectiveness of the Mongolian Iron Horse is not insignificant. Even in ancient history, the combat effectiveness of the Mongolian Iron Horse can be listed one by one. At its peak, Mongol cavalry flattened Europe and swept across Eurasia.
At its peak, the Mongol Iron Horse was invincible. So the question is, why can't the Mongol cavalry of the Yuan Dynasty defeat the Eight Banners cavalry of the Qing Dynasty? You know, the cavalry of the Eight Banners is very powerful, and at the same time, the strength of the Mongolian Iron Horse is not insignificant. Judging from the comparison of achievements, the Mongolian Iron Horse's record is even better.
In terms of the territory occupied, the strength of the Mongol cavalry was much stronger than that of the Eight Banners cavalry. After the establishment of the Yuan Dynasty, the footprints of the Mongols did not stop, and at its most glorious time, the territory of the Yuan Dynasty reached more than 40 million square kilometers, thus becoming the largest empire in history. It can be said that the footprints of Mongols were almost all found in the world at that time. But the question is, why did the mighty nation, the mighty Mongol Iron Horse, end up in obscurity? In the Mongol Empire and the Yuan Dynasty, there were many warlike generals, and at this time the Mongol Iron Horse reached its most glorious time. After the Mongols passed, the mongols seemed to have declined in strength, when a local force emerged.
This is Jurchen. At the end of the Ming Dynasty and the beginning of the Qing Dynasty, the Jurchen clan gradually arose. At that time, the founding emperor of the Liao State, Yelü Abaoji, had this evaluation of Jurchen: "'Jurchen is dissatisfied with ten thousand, full of ten thousand invincible'", through this evaluation, Jurchen and Mongolian iron horse are almost on par. So if the two sides are at war, who is more powerful? According to today's calculations, the Mongol Iron Horse was defeated. During the Jin Dynasty, the Mongols were oppressed for the simple reason that they were not of the same kind, and their hearts must be different. In this case, the Mongol people at that time were humiliated. From this point of view, the greatness of Genghis Khan is also reflected, that is, Genghis Khan unified the people of the steppe into his camp.
In this way, the fighting power of the Mongols exploded. Therefore, the reason why the Mongols could not defeat Jurchen was also very simple, that is, the Mongols finally divided. The rise of the Mongols was associated with Genghis Khan's unification of the Mongol tribes. At the end of the Yuan Dynasty, the Mongol nation began to gradually split, and the Mongol nation at this time was no longer united.
During the Yuan Dynasty, Mongolia was divided into several khanates, and the Mongol tribes were no longer united. At the same time, the khanate was disloyal. During the Ming Dynasty, the Mongol nation split into the Wala and Tatars. Even at this time, the Mongols had been driven out of the Central Plains, and by this time the Mongols' combat effectiveness had been greatly reduced. At the end of the Ming Dynasty, a very interesting phenomenon appeared.
This phenomenon is that in the army of the Ming Dynasty, there were Mongol cavalry, and even in the Later Jin Dynasty at that time, there were also Mongolian cavalry. When the Mongols split, the Jurchens gradually moved towards unification. At the end of the Ming Dynasty and the beginning of the Qing Dynasty, the Mongol cavalry was already a light cavalry, and the Mongol cavalry at this time had lost its glory. At this time, the Mongol cavalry lacked both armor and heavy cavalry, and had no impact.
After the mongol split, it had completely declined, and after the Jin Dynasty had a counselor Fan Cheng, the Mongols had the opposite, and there were almost no counselors. More importantly, the Mongols have never produced any outstanding generals, and the Qing Dynasty has only been talented for a few decades. In addition to cavalry, even in battlefield command, the Mongols were at a disadvantage.
Since the founding of the Yuan Dynasty, Mongolia has not studied Han culture, and compared with the Jurchens, the Jurchens are constantly learning Han culture. The earliest example is Nurhaci's reuse of the Han Xiang Fan Wencheng. It is worth mentioning that Fan Wencheng assisted the four emperors of Qing Taizu, Qing Taizong, Qing Shizu and Qing Shengzu in his lifetime, and was a very important minister in the early Qing Dynasty.