Secession in China

The People's Republic of China and the Republic of China insist sole legitimacy of China against each other. Practically, the former is administering Mainland China and the two special administrative regions of Hong Kong and Macau and the latter is administering the Taiwan area.
Mainland China.
Inner Mongolia
Tibet Autonomous Region
Xinjiang Autonomous Region
Special administrative regions.
Hong Kong
Taiwan area.
Taiwan
In perspective of the laws of the Republic of China, the Taiwan Independence movement is considered as "secessionism", but practically, the movement seeks to "replace" the ROC with the Republic of Taiwan because Taiwan area is the only practical region administered by the ROC.
In perspective of the laws of the People's Republic of China, the Taiwan Independence movement is considered as "secessionism", too because the PRC considers the Taiwan area as its integral part as a rogue province.