In 118 B.C., coins "Wuzhu" (five "zhu", a "zhu"-a weight unit approximately 0.66 gram) were cast. The currency system "Wuzhu" had since been established. After the Eastern Han, the currency system "Wuzhu" was undermined by the appearance of various inferior coins. At the end of the Western Han, Wang Mang waged four reforms of currency system. The reforms failed due to the fact that the grading category was too complicated. However, coins of this period were well known for their elegant style and fine workmanship.