2-Mun Coin 1742-1752 Copper diameter 28 mm, weight 4.78 g The "Sang p'yong t'ong bo" was the chief copper coin in circulation in Korea between 1633 and 1883. The inscription means "Stable currency" and derives from the name of the institution that began the issue of these coins the "Bureau for Stabilization". This institution laid up stocks of grain in years when the harvest was good so as to use them when the crops failed, a common practice in the Far East. The wording on the obverse remained the same throughout the period of issue. Only the inscriptions on the reverse that occupied between one and all four divisions of the face varied. They contained the device of one of the 57 mints and also the number of the furnace from which the coin was cast and the serial "number" of the issue. The latter was expressed as one of the first sixteen symbols in the classic book "The Thousand Character Classic" which served as indicators of ordinal position, in the same way as we use letters of the alphabet. The smallest unit of currency was the mun, 100 moons made a yang, 10 yangs made a hvan. On the obverse of the example shown, the upper field contains the device of the Mint of the Military Transport Authority, the lower field the third symbol from the book, meaning "primaeval chaos".