In 1964, a major split occurred in the Communist Party of India. The split was the culmination of decades of tensions and factional infighting. When India became independent in 1947, differences arose of how to adapt to the new situation. As relations between the Nehru government and the Soviet Union improved, a faction that sought cooperation with the dominant Indian National Congress emerged within CPI. This tendency was led by S.A. Dange, whose role in the party hierarchy became increasingly controversial. When the Sino-Indian War broke out in 1962 Dange's opponents within CPI were jailed, but when they were released they sought to challenge his leadership. In 1964 the party was finally divided into two, with the left faction forming the Communist Party of India (Marxist). The split had a lot of regional variations. It also impacted other organizations, such as trade union and peasant movements. The split has been studied extensively by scholars, who have sought to analyze the various domestic and international factors involved.

The Communist Party of India (CPI) is the oldest communist party in India. The CPI was founded in modern-day Kanpur on 26 December 1925.