- 1920s to 1930s
- 1930s to 1940s
- 1940s to 1950s
- 1950s to 1960s
Answer: 1930s to 1940s
Explanation: The communist movement in Bengal solidified and gained significant momentum during the 1930s to 1940s. This transformative era witnessed the formation and consolidation of communist ideologies and organizations, leaving a lasting impact on the political and social landscape of the region.