Ban Liang Qian is the round coin wth a quadrate hole.In the Qin Dynasty, Emperor Qin Shi Huang unified the monetary policy and ecouraged the use of Ban Liang Qian. This kind of coins were not used until the Western Han Dynasty. Even in the early Western Han, they were still circulated. On the reign of the Emperor Wudi, China started to use Wu Zhu Qian.