The event that catalyzed the Chinese Civil War, leading to the establishment of the People's Republic of China, was the Japanese invasion in the 1930s, which created a temporary alliance between the Chinese Nationalist Party (Kuomintang) and the Chinese Communist Party. However, as the war against Japan drew to a close, tensions escalated between the two factions, leading to renewed conflict. By 1949, the Communist Party, led by Mao Zedong, emerged victorious, culminating in the formal declaration of the People’s Republic of China on October 1, 1949, fundamentally transforming Chinese political dynamics.