The Duoyan Three Guards were mercenaries of the Ming Dynasty, all composed of Mongolians. By the end of the Ming Dynasty, the Three Duoyan Guards had existed in name only, and later surrendered to the Houjin Dynasty. They could be said to be accomplices of the Manchu Qing Dynasty, but they were not the main cause of the fall of the Ming Dynasty.
First of all, among the three Duoyan guards, the Fuyu Guards and the Taining Guards began to be occupied by the left-wing Chahar Tribe (directly subordinate to Dayan Khan and his successors), the Horqin Tribe and the Kahar Tribe during the Jiajing Period. Erkha was divided and annexed. After the Wanli Year of the Ming Dynasty, the records of interactions between the leaders of the Fuyu Guard and Taining Guard and the Ming Dynasty completely disappeared, indicating that they had completely melted into the various Mongolian tribes.
In fact, during the entire existence of the Duoyan Sanwei, they often colluded with the Tatar forces to invade the Ming Dynasty and acted as the Tatar guide and partner. However, the Ming Dynasty fought back and forth with the Mongolian forces. For more than a hundred years, the Ming Dynasty failed to fall. It can be seen that the Duoyan Three Guards or the Mongolian forces were indeed only a secondary reason for the demise of the Ming Dynasty, not the main reason.
The reason that caused the demise of the Ming Dynasty was first of all the Ming Dynasty itself. At the end of the Ming Dynasty, problems such as corruption of officials, deterioration of the combat effectiveness of the army, serious land annexation, and natural disasters broke out. Of course, the strength of the Ming Dynasty could not be compared with that of the early and middle stages.
The second reason is that the Houjin Dynasty established by the Jurchens in the Northeast is indeed stronger than Mongolia, and its concentrated expression lies in its productivity and institutional advantages.
In terms of system construction, after Huang Taiji succeeded to the throne, he carried out vigorous reforms to weaken the power of the Baylors, imitated the Ming system, rectified and reformed the national institutions, ensured his exclusive status, and centralized power to the central government The feudalized country was excessive, and Mongolia's patriarchal feudal system could easily lead to disintegration. The centralized political system of the Later Jin Dynasty was far more vital than the patriarchal feudal system of Mongolia.
In short, neither the Duoyan Three Guards nor the surrender of Monan Mongolia to the Later Jin (Qing Dynasty) could be the main reason for the demise of the Ming Dynasty. The demise of the Ming Dynasty was due to its own decline and the encounter with an army far more powerful than Mongolia. The emerging political power and the combination of internal and external factors caused the demise of the Ming Dynasty.