After the establishment of the Song Dynasty, they realized the importance of a unified currency, set out to clean up the old currency, and established a coinage supervisor. After Song Taizu acceded to the throne, he banned the circulation of bad money and iron money. Those who fail to pay the money are guilty, and private investors abandon the market. In the second year of Song Taizong Taiping Xingguo (977), it was stipulated that copper coins must be more than four and a half pounds per penetration to circulate. Through the efforts of the three dynasties in the early Song Dynasty, four coin-casting prisons, namely, Yongping Prison in Raozhou, Yongfeng Prison in Chizhou, Guo Feng Prison in Jianzhou and Guangning Prison in Jiangzhou, were successively built, so that the amount of copper coins cast in the Northern Song Dynasty reached 6.5438+0.25 million. At this time, the national monetary system was basically unified except Sichuan. Small coins in circulation in the market are of good quality and reasonable formula. They weigh 5 kilograms per 1000 dollars and use 3 kilograms of copper, 8 ounces of lead and 8 ounces of tin. The quality of copper coins is good and the market runs fast. When we arrived in Song Shenzong, the country was rich and prosperous. Therefore, the Song Dynasty set up 1 1 coinage supervisor, which increased the number of copper coin supervisors to 15. At the end of Xining, the amount of copper coins cast reached 3.73 million pieces, and in Yuanfeng three years (1080), it reached 5.06 million pieces, which was the highest in the Northern Song Dynasty. Throughout the Northern Song Dynasty, the number of copper coins was 260 million. After seven years in Xuanhe, Song Huizong (1 125), the amount of copper coins was 262.04 million.

The earliest change of monetary policy in the Northern Song Dynasty was in the northwest of Song Renzong. At that time, in order to resist the invasion of Xixia, the Northern Song Dynasty assembled about 300,000 troops in the northwest. Such a huge military establishment has brought great pressure to finance. In order to solve the problem of military supplies, the Northern Song Dynasty began to cast large copper coins and iron coins in Hedong and Shaanxi. In the first year of Emperor Renzong's Kangding (1040), large copper coins were cast for the first time, with one as ten, but the actual weight was only three times that of small flat coins. There are also two kinds of iron coins, one big iron coin and ten small iron coins, but iron is cheap and copper is expensive, and the court can get three times the profit. Because the value of large and small copper coins and large and small iron coins is much lower than the actual currency value, Xiaoping coins, as equivalents, lose their equivalent meaning, which leads to serious currency confusion in northwest China. Because there are huge profits in casting money, people steal casting bees, and for a time, bad money is popular, and a large number of high-quality Xiaoping coins are squeezed out of circulation. In the eighth year of Li Qing (1048), the monetary policy in northwest China was adjusted in the Northern Song Dynasty. The big copper coins were reduced to one to three, the big iron coins to one to three, and the small iron coins to three to one. In four years, Jiayou made another adjustment. Two big copper coins and two big iron coins. Small iron coins are forbidden to circulate in Shaanxi, only in Hedong. After four years of adjustment (1059), the monetary policy in northwest China tends to be stable. The value of big iron coins kept a one-to-one exchange ratio with small flat coins for quite a period of time, which made the commodity economy in northwest China develop continuously and solved the problem of military supplies at the same time.

In the second year of Chongning (1 103), Cai Jing was promoted to one of the top ten copper coins. When nine catties of copper, seven taels, half lead and one third tin are used in the top ten coins, usually these materials are only enough to cover the cost of three copper coins, which leads to the proliferation of private casting. Under the impact of big copper coins, some small copper coins withdrew from the circulation field, while others were melted into big money again. In the fourth year of Chongning (1 105), Cai Jing went on strike, and the court ordered that the ten yuan of Jinghu South Road, Jiangnan East-West Road, Liangzhe Road and Huainan Road be changed to five yuan. In the first year of Daguan (1 107), Cai Jing was reintroduced, and it was promoted to the top ten money again. At the same time, when promoting the top ten money, it also cast tin money. Tin coins are iron coins mixed with lead and tin, and one tin coin is used as two small copper coins. At first, tin money only circulated in the northwest, and then it was gradually spread to the whole country by Cai Jing. The exchange rate of tin coins was much higher than its value and soon began to depreciate. The currency containing tin has the longest circulation time and the most serious harm in Guanzhong area.