How did the Han dynasty use the Great Wall to control trade and travel?

During the Han dynasty, the Great Wall served as a vital instrument for centralizing control over trade and travel, functioning as a boundary between Chinese provinces and the outside world.12

The wall facilitated the growth of the Silk Road by providing a protected causeway for diplomats and merchants traveling toward Central Asia. To manage this movement, the government implemented the following controls:12

• Traffic Regulation: Access was strictly monitored at specific points along the wall to screen incoming travelers and prevent the unauthorized departure of deserters or criminals.2
• Export Restrictions: The state enforced bans on the export of sensitive goods, specifically iron manufactures and weapons of war.2
• Infrastructure and Security: The wall featured a network of watch stations, forts, and castles—such as those described in the Juyan Hanjian—which allowed for disciplined garrison troops to conduct daily patrols and relay signals.12
• Commercial Oversight: Because the government sponsored export trade, the wall helped maintain state oversight of the exchange of Chinese silk for foreign animals and animal products.2