"A while" as in about 400 years — that's when China took over Taiwan.
After World War II, there was a power struggle between the Republic of China (backed by the USA) and the Chinese Communist Party (backed by Russia).
The ROC/US controlled pretty much all of China, but then the US withdrew support and simultaneously granted concessions to Japan (as part of the peace deal between Japan and the US) and the CCP/Russia took advantage. The resulting civil war "ended" with the ROC having control of Taiwan, and the CCP controlling all of the rest of China.
But that civil war never really ended - it merely cooled down and became non-military conflict.