This bronze coin, excavated at the Archaeological Site in Yongyeon-dong, Wiwon-gun, Pyeonganbuk-do, was called a myeongdojeon (or Mingdaoqian in Chinese) due to its knife-like shape.. The coin appeared during the late Spring and Autumn Period and was widely circulated during the following Warring States Period. Similar coins unearthed on the Korean Peninsula, largely to the north of the Daedonggang River, were made during the Yan Dynasty (323-222 BCE). Historians believe that the coins were brought to the Korean Peninsula during the late Warring States Period when Chinese culture, including iron manufacturing techniques, was introduced there.