Complex sentence: In the 1960s, the party experienced internal problems, with a split between supporters of the Soviet Union under the "revisionist" Khrushchev and supporters of China under Mao Zedong.
Split into simpler sentences: In the 1960s, the party experienced internal problems due to the Sino-Soviet split. The party was divided between supporters of the Soviet Union under the "revisionist" Khrushchev and supporters of China under Mao Zedong.