Complex sentence: A large number of the White Terror's victims were mainland Chinese who usually owed their evacuation to Taiwan to the KMT, and, often having come unaccompanied to Taiwan, were considered more disposable than local Taiwanese.
Split into simpler sentences: A large number of the White Terror's victims were mainland Chinese, many of whom owed their evacuation to Taiwan to the KMT. Often, after having come unaccompanied to Taiwan, these refugees to Taiwan were considered more disposable than local Taiwanese.