Yanyan understood. This was Li Mu's scorched-earth policy: rather than clashing head-on with the Hu people, they would retreat into the walled cities and bolt the gates whenever the Hu forces swept south.
This way, the Hu people could no longer pillage enough provisions from the Northern Frontier of the State of Zhao to get through the winter, while the people of the Northern Frontier were spared their ravages.
"How long has this been going on?" Yanyan asked again.
Chapter 138