The Ryukyuan mon was the currency used in the Ryukyu Islands. The Ryukyuan monetary system was based on that of China, like those of many nations in the Sinosphere, with the mon serving as the basic unit, just as with the Japanese mon, Vietnamese văn, and Korean mun. Like Japan had also done for centuries, the Ryukyuans often made use of the already-existing Chinese cash coins when physical currency was needed.

The mon was the currency of Japan from the Muromachi period in 1336 until the early Meiji period in 1870. It co-circulated with the new sen until 1891. Throughout Japanese history, there were many styles of currency of many shapes, styles, designs, sizes and materials, including gold, silver, bronze, etc. The kanji for mon (文) also shares its name with Chinese wén, Korean mun, Vietnamese văn.