Ryuukyuuan coins
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The Ryuukyuus are today known as Okinawa Prefecture. They are are string of islands stretching in an arc from Japan's Kyuushuu Island down toward Taiwan. Previous smaller kingdoms were unified into an independent kingdom by the Sho family in the early 1400's. The first locally made coin was the Taise Tsuuhou begun in 1454. The next was the Setaka Tsuuhou, first minted in 1461. Despite the fact that the Ryuukyuu's were not a large kingdom, the number of these coins minted was quite large and they are not too uncommon. One other coin, the Kin'en Sehou (1470) is more hard to find. After this, local mintings of standard 1 mon coins seem to have stopped and Chinese coinage relied upon.
In 1609 the Shimazu clan, rulers of the Kyuushuu domainal country of Satsuma, sent an army to conquer the Ryuukyus and took the king Sho Nei as hostage. The Tokugawa overlords away in Edo allowed the Shimazu clan to claim the Ryuukyuu's for their own as a subject kingdom. The Sho were returned and remained kings of the still relatively independent Ryuukyuus but were subject to taxation and indirect rule by the Shimazu house until the 1870's. At the same time the Ryuukyuus were treated as an independent periphery kingdom by the Ming, and later the Qing (Ch'ing) dynasty of China. Thus the Ryuukyuus had a very complex political identity between 1609 and 1879 when they were fully incorporated into the Japanese Meiji state, as Okinawa Prefecture.
During the late Tokugawa and early Meiji period Satsuma domain, like many domains within Japan, wished to mint its own currency, and also to manufacture counterfeit 100 mon Tenpou Tsuuhou coins, in order to improve government finances. It achieved this partly by the cover of manufacturing coins for use within the Ryuukyuu kingdom. The 100 mon Ryuukyuu Tsuuhou (1863-) is very similar to the Tenpou Tsuuhou. The Hanshu Ryuukyuu Tsuuyou (1863-) is large, round and not like any Japanese coin. 
 
 
Early Ryuukyuu 
The Setaka Tsuuhou pictured below on the left was minted during the reign of the king Sho Toku between 1461 and 1470. One fascinating thing about how this coin was made is that the manufacturer took the Chinese coin Yung Lo Tong Bao (J. Eiraku Tsuuhou), carved away the Yung Lo characters and replaced them with the Sekou characters. Notice how the Sekou (top and bottom) characters are rounded while the Tong Bao characters are angular. Also notice the curious left and right shifting of the Sekou characters relative to the center hole.
source: Nihon Ginkou Chousakyoku ed., Zuroku Nihon no kahei, vol.1 (Tokyo: Touyou Keizai Shinpousha, 1973), p. 105
The coin below was dug from the bottom of the Berantas river in Java, Indonesia. Mostly Chinese, but also Japanese, Annamese (Vietnam), Malayan and Ryuukyuuan coins are dug up there regularly. This is a testament to the international nature of cash coinage. This one seems to be nearly uncirculated and may have been sunk on its first trip from the Ryuukyuu's. 
A Yung Lo Tong Bao is pictured to the right for comparison. Because copper shrinks when it cools the Setaka Tsuuhou is a touch smaller than the standard Yung Lo Tong Bao which was used as the base of the "parent coin" in manufacture. The Yung Lo Tong Bao was produced in such quantities by the Ming for foreign consumption, and so many circulated in Japan that in the 16th century in Japan the word "Ei" (Ch. Yung) meant "copper money." 
Setaka Tsuuhou
1461
23mm wide x 1mm thick
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Setaka Tsuuhou verso
Dr. Luke Shepherd Roberts
Attribution
<a rel="nofollow" class="external text" href="http://www.history.ucsb.edu/faculty/roberts/coins/Ryuukyuucoins.html">Ryuukyuuan coins</a> (University of California at Santa Barbara)