If they wanted to increase the revenue of the government office, they had to have a pillar industry. It was far from enough to rely solely on taxes and documents.
There were already profitable industries such as salt, tea leaves, and brocade. Even if they wanted to improve the quality, it would not work. For example, there were four grades of salt circulating in the market: ordinary salt, refined salt, high-quality salt, and top-grade salt.
