Asian diplomatic envoys to China visit the Datong Mass Graves Memorial in Datong, Shanxi province, on Wednesday. The Japanese occupation of the coal mines in Datong during the Chinese People's War of Resistance Against Japanese Aggression (1931-45) resulted in the exploitation of coal resources, harsh working conditions and the discovery of mass graves. During the occupation, coal production in Datong increased from 870,000 metric tons in 1938 to 2.27 million tons in 1942. Over 60,000 miners lost their lives.