English: When Emperor Wu conquered the land to the west of the Yellow River, large numbers of Han settlers settled there, displacing local nomadic tribes. Prefectures and districts were established and soldier farmers were sent to guard the frontier. Large quantities of objects belonging to Chinese cultural relics of farmer-soldiers, including books, poetry on wooden slips and educational materials were left in frontier defence towns like Chu-yen, Tun-huang. Their presence clearly indicates the spread of Chinese culture.