In 1981, the so called 'Gang of Four' were put on trial for their role in which period of Chinese history?

The Gang of Four was a political faction composed of four Chinese Communist Party officials. They came to prominence during the Cultural Revolution (1966–76) and were later charged with a series of treasonous crimes. The gang's leading figure was Mao Zedong's last wife Jiang Qing. The other members were Zhang Chunqiao, Yao Wenyuan, and Wang Hongwen.

The Gang of Four controlled the power organs of the Communist Party of China through the later stages of the Cultural Revolution, although it remains unclear which major decisions were made by Mao Zedong and carried out by the Gang, and which were the result of the Gang of Four's own planning.

The Gang of Four, together with disgraced general Lin Biao who died in 1971, were labeled the two major "counter-revolutionary forces" of the Cultural Revolution and officially blamed by the Chinese government for the worst excesses of the societal chaos that ensued during the ten years of turmoil. Their downfall on October 6, 1976, a mere month after Mao's death, brought about major celebrations on the streets of Beijing and marked the end of a turbulent political era in China.