What did Hannah emperors do to keep the economy stable?

There is no historical record of any Hannah emperors. It is likely that you are referring to the Han emperors of ancient China. The Han Dynasty (206 BCE - 220 CE) implemented several measures to maintain a stable economy. Some of these measures include:

1. Agriculture Reforms: The Han emperors introduced land reforms to redistribute land ownership, increase agricultural productivity, and ensure sufficient food supply. They also supported irrigation systems and provided loans and assistance to farmers.

2. Silk Road Trade: The Han Dynasty encouraged trade along the Silk Road, which connected China to the West. This boosted international commerce, facilitated cultural exchanges, and brought wealth to the empire.

3. Currency Standardization: The Han emperors implemented a standardized currency system, which included the banliang coin. This eased trade and provided stability to the economy.

4. State Monopolies: The Han Dynasty established monopolies over salt, iron, and liquor production. This allowed the emperors to control prices, ensure quality, and generate revenue for the state.

5. Public Works Projects: The emperors invested in extensive infrastructure projects like canals, roads, and granaries. These projects provided employment opportunities and improved transportation, aiding in economic growth.

6. Tax Reforms: The Han emperors implemented policies to ensure fair tax collection and reduce oppressive taxation practices. This helped alleviate the burden on farmers and middle-class citizens.

These measures contributed to the stability and prosperity of the Han Dynasty's economy for several centuries.