Meanwhile, the newly formed Chinese government was trying to reassert its authority over the country after over a decade of fragmented warlord dominance. They started to claim that treaties between China and Japan were invalid. China also announced new acts, so the Japanese people (including Koreans and Taiwanese as both regions were under Japanese rule at this time) who settled frontier lands, opened stores or built their own houses in China were expelled without any compensation. Manchurian warlord Zhang Zuolin tried to deprive Japanese concessions too, but he was assassinated by the Japanese Kwantung Army. Zhang Xueliang, Zhang Zuolin's son and successor, joined the Nanjing Government led by Chiang Kai-shek from anti-Japanese sentiment. Official Japanese objections to the oppression against Japanese nationals within China were rejected by the Chinese authorities.