Which goods were restricted from leaving China through the Great Wall during the Han dynasty?

During the Han dynasty, the Great Wall of China served as a boundary to control traffic and manage trade. To maintain security and state interests, the government imposed a ban on the export of specific goods, most notably iron manufactures and weapons of war.1

Beyond restricting these strategic items, the wall functioned as a checkpoint to monitor travelers and prevent the unauthorized departure of criminals or deserters from the empire.1