Original sentence: In 1949, after losing control most of mainland China following the Chinese Civil War, and before the post-war peace treaties had come into effect, the ROC government under the KMT withdrew to occupied Taiwan.Some argue that this made the ROC a government in exile, and Chiang Kai-shek declared martial law.while others maintain it is a rump state while others regard it as a government in exile..  The treaties left the status of Taiwan—as ruled by the ROC or PRC—deliberately vague, and the question of legitimate sovereignty over China is why China was not included in the San Francisco Peace Treaty
Edited sentence: In 1949, after losing control most of mainland China following the Chinese Civil War, and before the post-war peace treaties had come into effect, the ROC government under the KMT withdrew to occupied Taiwan (which was still Japanese territory), thus becoming a government in exile, and Chiang Kai-shek declared martial law.The treaties left the status of Taiwan—as ruled by the ROC or PRC—deliberately vague, and the question of legitimate sovereignty over China is why China was not included in the San Francisco Peace Treaty