Abstract: The paper investigates the historical agricultural exploitation in Northwest China, and its social benefits in the context of historical documents and their relationship with temperature and humidity backgrounds. Results show that during the Western Han Dynasty (206 BC-25 AD) and the early stage of Tang Dynasty (ca.7th century) climate was suitable for agriculture, leading to the success of large-scale wasteland reclamation in Gansu Province (called Hexi area in history), however during the late stage of the Tang Dynasty (ca. 8th-9th century) and the middle of the Ming Dynasty (ca.16th century), the climate there went into a cold stage, leading to the decline of stationing troops who opened up wasteland in the region; the prosperity of the Tarim Basin at the beginning of the Christian Era and its subsequent decline were linked to changes in water resources; and historically, the reclamation and later desertion were responsible for accelerating land desertification, and its typical examples are the formation of the Wulanbuhe Desert and the frequent occurrence of severe sand storm events in the warmer 13th century as the bad aftermath of the desertification.

Key words: Northwest China, historical climate, environmental change, agricultural exploitation, reclamation and desertion, historical documentary records