Japanese can conquer Korean peninsula, why can't China?

The fundamental reason is that Inner Mongolia and Northeast China have always been under the actual control of the northern minorities. In order to achieve effective control of the Korean peninsula, the central plains regime must first achieve effective control of Inner Mongolia and Northeast China.

This is why only in the Yuan, Ming and Qing Dynasties did North Korea surrender to China and become a vassal of China. This is why even if Koguryo was destroyed by Xue in the Tang Dynasty, the Governor's Office of Anton could not effectively control the Korean Peninsula. Because as long as there is a problem in Inner Mongolia and Northeast China, the connection between the Central Plains and North Korea will be interrupted immediately, and it is impossible to control the Korean Peninsula.

Between Japan and the Korean peninsula, there is only a narrow sea area where the Yellow Sea and the Sea of Japan meet. As long as Japan can gain the right to control the sea in this sea area, it can ensure its ties with the Korean Peninsula and maintain its control over the Korean Peninsula.

Toyotomi Hideyoshi's two expeditions ended in failure. Because he can't get the sea control right in front of the navies of Li Shunchen, China and North Korea.

The key to Japan's occupation of the Korean peninsula in modern times lies in the victory of the Yellow Sea naval battle. Otherwise, even if the Qing army collapses thousands of miles on land. As long as Beiyang navy can keep the sea power here. Then, in the Sino-Japanese War of 1894-1895, Japan could only follow the old path of Toyotomi Hideyoshi.

Therefore, from the above comparison, it can be seen that China's control of the Korean Peninsula is different from that of Japan. If China's Central Plains regime wants to actually control North Korea, it must first realize the stable control of Inner Mongolia and Northeast China, and then realize the control of the Korean Peninsula. Japan only needs to control the waters near the junction of the Yellow Sea and the Sea of Japan, and it has the opportunity to control the Korean Peninsula.