From the time of their development, and until the introduction of the western currency system, Chinese coins were cast, not minted; the typical coin material was bronze. Initially, the coins' value generally corresponded to their weight. This meant that a bronze coin of 5 shu (wu shu) weighed 5 shu (about 4 grams), and was worth 5 shu of bronze. This tiny coin was cast in the Kingdom of Wei, a short-lived state that emerged after the fall of the Han dynasty in 220 AD. In Wei, debased wu shus were issued that circulated until the time of the Jin dynasty (265-317). Additionally to bronze coins silk and grain circulated as means of payment in Wei.