SinoCentrism

 China would have kept all of Korea if China didnt give Korea to Japan in the SinoJapanese war. You have to understand. It wasnt just Koreans in China that belonged to China. But the Koreans in Korea too.

Date     1 August 1894 – 17 April 1895
Location     Korea, Manchuria, Taiwan, Yellow Sea
Result     Japanese victory; a significant loss of prestige for the Qing Dynasty. Korea becomes independent from China.
Territorial
changes     China loses the influence of the Korean Peninsula to the Empire of Japan.
Qing Dynasty China cedes Taiwan, Penghu, and the Liaodong Peninsula to the Empire of Japan.
Belligerents
Qing Dynasty Qing Empire      Empire of Japan
Commanders and leaders
Qing Dynasty Empress Dowager Cixi
Qing Dynasty Li Hongzhang
Qing Dynasty Ding Ruchang  †
Qing Dynasty Deng Shichang  †     Empire of Japan Itō Hirobumi
Empire of Japan Yamagata Aritomo
Empire of Japan Itō Suke


Article 1: China recognizes definitively the full and complete independence and autonomy of Korea, and, in consequence, the payment of tribute and the performance of ceremonies and formalities by Korea to China, that are in derogation of such independence and autonomy, shall wholly cease for the future.

  This isnt the first time China will fight to defend its Korean territories from other nation-states. But this will be the first time China effectively loses it to Japan.