Complex sentence: Both China and Vietnam claimed victory in the last of the Indochina Wars of the 20th century; as Vietnamese troops remained in Cambodia until 1989, it can be said that China was unsuccessful in their goal of dissuading Vietnam from involvement in Cambodia.
Split into simpler sentences: Both China and Vietnam claimed victory in the last of the Indochina Wars. As Vietnamese troops remained in Cambodia until 1989, it can be said that China was unsuccessful in their goal of dissuading Vietnam from involvement in Cambodia.