In the first stage, money was gradually formed in Shang and Zhou Dynasties before Qin Dynasty. During the Spring and Autumn Period and the Warring States Period, the monetary economy developed greatly, and four monetary systems of cloth, knife, money and Chu coins appeared, which were unified in the Qin Dynasty. In the early Han Dynasty, we inherited the Qin system and changed the currency nine times before finding a more suitable "functional currency".

The second stage is the five-baht money system, from the fifth year of Emperor founding ceremony (1 18 BC) to the fourth year of Tang Wude (62 1 year) * * 738. In the meantime, there were two major changes, namely, Wang Mang's retro monetary system, the distribution of power in the Northern Zhou Dynasty, the supplement of the five elements and other currencies.

The third stage is Bao Tong's money system, from the fourth year of Tang Gaozu Wude (62 1) to the third year of Qing Dynasty (19 1 1), * * is 129 1, and money is no longer named by weight.

The fourth stage is the copper yuan period, from the late Qing Dynasty to the Northern Expedition, about 30 years.