Nomonhan is a small village near the border between Mongolia and Manchuria, China south of the Chinese city of Manzhouli .

In the summer of 1939 it was the location of the Nomonhan Incident, as it is termed in Japan, or the Battle of Khalkhin Gol as it is known in Russia. At this time Manchuria was a client state of Japan, known as Manchukuo. The Japanese maintained that the border between the two states was the Halha River (also known as the Halhin Gol, or in Russian as the Khalkhin Gol), while the Mongolians and their Russian allies maintained that it ran some 16 kilometres/10 miles east of the river, just east of Nomonhan village.

After the battle the Manchukuo-Mongolia Commission established a border, in an agreement signed on October 15, 1941. After the war these maps were used in the war crimes trials of Japan. China later requested the maps claiming it would not accept any border established by negotiation with the Japanese; however, the maps have disappeared and have not been located in either United States or Japanese archives. The official boundary between China and Mongolia was set in treaties in 1962 and 1964.