Several Chinese military organizations fought on the side of Japan in the 1930s and 1940s, and these were affiliated with more than one collaborationist regime. Japan occupied Manchuria, or northeast China, in 1931. A puppet state called Manchukuo was organized to administer this area in 1932. After the Sino-Japanese War began in 1937, most of China's populated area came under Japanese occupation. Wang Jingwei, a defector from China's ruling Nationalist Party, led the Nanjing Nationalist Government in 1940-1945. This regime administered eastern China.