Complex sentence: After the Communists won the Chinese Civil War in 1949, there were perceived similarities between Mao Zedong and Cao Cao, so Chinese propagandists began a long term and sustained effort to improve the image of Cao Cao in popular culture.
Split into simpler sentences: After the Communists won the Chinese Civil War in 1949, many people in China began to believe that there were many similarities between Cao Cao and Mao Zedong. Because of this perceived similarity, propagandists began a long term and sustained effort to improve the image of Cao Cao in Chinese popular culture.