Economic Importance 5. The main economic value of INDO-CHINA to Japan lies in the large production of rice and coal, particularly anthracite. It also contains valuable additions to Japanese supplies of zinc phosphate and salt. 6. INDO-CHINA is also of value to Japan owing to its common frontier with Southern CHINA. This enables smuggling to take place from the rich mineral provinces of YUNNAN and KWANGSI. 7. During the five months before the 7th December, 1941, INDO-CHINA was virtually subject to Japan.