Sulfur

• Other Names: sulphur
• Japanese: 硫黄 (iou)

Sulfur is a yellow mineral essential to the production of gunpowder.

One of the chief sources of sulfur historically in the region around Japan was the island of Iô Torishima, located in the Amami Islands to the south of Kyushu and controlled by the Ryûkyû Kingdom throughout the Edo period. China imported sulfur from the kingdom as well as from other sources, but forbade the export of the material. This made trade relations with (or control of) Ryûkyû vital for military preparedness, and powers throughout the region regularly worked to secure or maintain sources of Ryûkyûan sulfur. Ryûkyû often traded sulfur to entities in Japan, Korea, and China, or presented it as tax or tribute; in trade with Southeast Asia, however, Ryûkyû only ever shipped sulfur to Siam, and not to other polities. Japanese entities such as the Heian court and Muromachi shogunate exported a portion of the Ryûkyûan sulfur they obtained, in sizable enough amounts that sulfur is noted as one of the chief exports of premodern Japan.<ref>Richard von Glahn, "The Ningbo-Hakata Merchant Network and the Reorientation of East Asian Maritime Trade, 1150-1350," Harvard Journal of Asiatic Studies 74:2 (2014), 268-269.; Asato Susumu 安里進, Dana Masayuki 田名真之, et al. (eds.), Okinawa ken no rekishi 沖縄県の歴史, Tokyo: Yamakawa shuppan (2010), 117.<ref>