Partai Komunis Indonesia (PKI) was a political party in Indonesia that was founded in 1920. It aimed to promote communist ideology and sought to represent the working class and peasants. The party gained significant influence in the 1950s and 1960s, becoming one of the largest communist parties outside the Soviet Union. However, in 1965, a failed coup attempt led to a violent anti-communist purge, resulting in the mass killing of PKI members and sympathizers. The party was subsequently banned, and its influence in Indonesian politics diminished significantly, marking a pivotal moment in the country's history.