In 1931, Japan invaded and occupied Manchuria, the northern-most province of China, setting up a puppet regime and renaming it Manchukuo. The words were written by Zheng Xiaoxu, the first premier of Manchukuo, and appear to be an attempt by the Japanese government to differentiate between the Chinese in Manchukuo and the rest of China, promoting their distinct nation.
Special thanks to: Wilson Lin for some of this information, Shu Zhang Sun for some additional information and the lyrics, and Jo Hyo-roe for the sheet music.