Answer:
The Cuo recommends to detect intrusion of enemies by surrounding them by sandy fields.
Explanation:
Chao Cuo was a Chinese politician, philosopher and writer who worked during the Han Dynasty. Many of his writings address the Xiongnu nomads of the North, who were a pressing concern for China during the Han dynasty. He also proposed a policy that would populate and defend frontier zones. The advisor was murdered in an attempt to mitigate the Rebellion of the Seven States.
