Abstract: The author explored historical volumns with the method of history geography and drew conclusion as follows:(1)《Wei Shu》(History of the Northern Wei Dynasty) recorded that Tuo Basi,emperor of Northern Wei Dynasty had hunted in desert area from today's Dalad Qi to Jungar Qi,the place is just the east of Hobq Desert.More proofs were found in《Shui Jing Zu·He Shui》,its author,Li Daoyuan recalled that he had ever followed the emperor to inspect "He Tao" region,and investigated desertification trend around "Ling Rong".He point out that fixed dune and semi fixed dune existed from Wujia River to today's Yellow River main channal.These records proved that the western Hobq Desert had been desertified in latter Northern Wei Dynasty(about AD494-AD527).(2) According to the statement in《Shui Jing Zhu·He shui》about the right branch of Yellow River in "Jin-Shann" Valley area:the upper Jia Lu River flow across "Sha Ling"(dune or loose mound covered by sand),it is guessed that the place is near the mordern sandyland area.Also,two branches of Salawusu river,originated from or flow across "Sha Ling".These indicate that the south boundary of Mu Us Desert was same as today's.(3) The two tombstones-Helianbebe praised Qiwu and HuYizhou praised Tongwan city,described two different places.The former praised a beautiful natural husbandary farm in left bank of Yellow River between Da Hei River and Hun He River.The latter refered to Tong Wan city and praised the city backing famous mountain(Bai Yu Mountain) and facing great flow(Na Lin River).Its position has important military meaning.(4) During the period from Qing Han northern Ordos plateau was under the control of dry grassland desert grassland climate.This kind of climate made the earth surface that made of sandy materials easy to appear aeolian sandy landform.On the other hand,backward herding manner of nomadic nationalities and great quantity of husbandary accelerated dersertification process.

Key words: historic times, Ordos plateau, desertification