The history of Inner Mongolia during the Second World War is complicated, with Japanese invasion and different kinds of resistance movements. In 1931, Manchuria came under the control of the Japanese puppet state Manchukuo, taking some Mongol areas in the Manchurian provinces (i.e., Hulunbuir and Jirim leagues) along. Rehe was also incorporated into Manchukuo in 1933, taking Juu Uda and Josutu leagues along with it.