What is the relationship between the appearance of iron farm tools and the popularization of Niu Geng and Shang Yang's political reform?

The appearance and popularization of iron farm tools in Niu Geng greatly developed agriculture, but the shortage of cultivated land and the old system hindered social progress, and the slavery era gradually failed to adapt to the development of the times. In order to seek the prosperity of the country, Shang Yang carried out political reforms.

Shang Yang's political reform violated the interests of the nobility. For example, his reward for meritorious service seriously damaged the interests of the nobility, and also led to the end that Shang Yang was finally dismembered by five horses.

Enlightenment: the development of the times needs constant reform; Reform will not be smooth sailing, and it needs to pay a price.