The formation of the CCP in 1921 was influenced by both internal and external factors, but was primarily driven by external factors such as the failure of Western liberalism demonstrated by the Treaty of Versailles, ideological influence from the Russian revolution and Lenin's theory of imperialism, and practical aid from Russian Communist agents sent by the Comintern to help create a revolutionary party in China. However, applying Communist ideology presented challenges in China given its large rural population and small urban proletariat that Communist theory was based around.