Complex sentence: The first major political party in China was the Kuomintang which is currently active only in Taiwan, which at the same time, there are also some Chinese mainlanders who claim to be the spritual party member.
Split into simpler sentences: The first major political party in China was the Kuomintang which is currently active only in Taiwan. At the same time, there are also some Chinese mainlanders who claim to be the spritual party member.