During Qin Xiaogong's political reform, Shang Yang vigorously promoted the policy of attaching importance to agriculture and restraining business, and its main measure was to collect the customs clearance tax and market business tax of merchants in the form of currency. In addition, in 348 BC, the "initial tax" was implemented, and the oral tax was levied on the people of the whole country, and the oral tax was also levied in the form of money.