The first legal tender in Korea, Sangpyeong Tongbo was issued in 1678 (the fourth year in the reign of King Sukjong of Joseon) and used nationwide for about 200 years until the late Joseon Dynasty. The name Sangpyeong is a shortened version of sang si pyeong joon, meaning "a consistent value at all times and easily usable by anyone." On the obverse of the coin, each letter of the word "sang, pyeong," (vertical) and "tong, bo" (horizontal) was stamped around a square hole in the middle, while the top of the reverse showed an abbreviation for the name of the mint. The Thousand-Character Classic, numeral letters, or codes were additionally printed later to stem counterfeiting and apportion blame. According to the unit of old Korean coinage, one Sangpyeong Tongbo equaled one Moon. One hundred Moon equaled ten Jeon, and ten Jeon equaled one Nyang.