国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

Sec. iii]   THE WALL BETWEEN Y0-MEN AND YANG KUAN   695

communication which linked the headquarters at T. xiv, i.e., as I assume, the Jade Gate, as well as the stations further east, with the nearest inhabited area at Nan-hu, or Yang kuan, would have been completely exposed.

In the absence of direct documentary evidence the explanation here offered cannot be considered as definitely proved. But it appears to me strongly supported, not only by all topographical facts but also by any historical information that the Chinese Annals furnish for this period. This retrenchment of the westernmost frontier line of the empire towards the end of Wang Mang's reign or very soon after would have been fully in keeping with a well-attested contemporary change in Chinese policy. Serious trouble had arisen about A. D. 9 with the Hsiung-nu, or Huns, through Wang Mang's action towards the Shan yii, their paramount chief, and disorders broke out in the ` Western Regions ', which the Chinese were unable to protect adequately against Hun raids from the north.6 After A.D. 16, the Former Han Annals tell us, the Hsiung-nu ` made a grand attack on the northern border ; while the Western Regions were broken up and scattered like loose tiles'. We are informed also that `-some years later (A.D. 23), when Wang Mang was dead ', the authority of the Chinese Governor-General of the Western Regions ` was annihilated, and the power of China in the Western Regions was at a minimum '.6

After the accession of the Later Han dynasty in A. D. 25 these conditions continued. As the Hou Han shu clearly states, the Western Regions during the first two reigns were allowed to remain under the power of the Huns, who during the period A.D. 58-75 even succeeded in making inroads into four commands of Ho-Iasi, including Tun-huang and westernmost Kan-su.7 It is certain that, during the half-century following Wang Mang's death, Chinese policy was no longer concerned about imperial expansion westwards, but, until the last quarter of the first century A. D., kept strictly on the defensive. The statements of the Later Han Annals are very precise on this point, and they afford additional justification for the belief that the retrenchment of the line of the Limes, which I assume to be represented by the transverse wall passing outside T. xiv, took place shortly before or during that period of passive defence on the westernmost frontier.

In the light which the topographical and historical facts just discussed shed upon the character and origin of this transverse wall, it is easy to realize that the direction of its line just towards T. xiv distinctly confirms the location there of the Jade Gate. By adopting this alignment for the new wall it was possible to retain the traditional site of the Yü-mên headquarters, and with it also the natural advantages of position for which it had originally been chosen. Equally important probably was another consideration. From the very beginning, when the western frontier of the empire was extended to the region of Tun-huang, we find the two ' barriers' of Yii-mén and Yang always mentioned in close conjunction by the Annals of both Han dynasties.8 There can be no doubt that the frontier troops stationed there were meant to offer mutual support. We have seen above that the ' Yang barrier' must be located at the present Nan-hu, and that the Jade Gate was certainly situated to the north-west of it and on the line defended by the main wall and watch-stations

Retrenchment due to Hun troubles.

Passive frontier defence during first cent.

A. D.

Jade Gate retained at T. :ay.

Cf. Chavannes, T`ou g pao, 1907, p. 155, note 2 ; Wylie,,. Anthrop. Inst., xi. p. 111.

6 Cf. Wylie, J. Anthrop. Inst., xi. p. rra. M. Chavannes, Documents, p. vii, seems to find some contradiction between the above statements of the Former Han Annals and the evidence of our contemporary records from the Limes. But the increased activity of the Chinese frontier guards beyond Tun-huang, which these records undoubtedly prove, is fully reconcilable with the decay of Chinese authority in the Tarim Basin and the renewed pressure exercised by the

Hun neighbours in the North. In reality, the latter facts account for the former.

Cf. Chavannes, T'oung pao, 1907, pp. 155 sqq. It was not until A.D. 73 that the first step of an offensive westwards was taken by the Chinese occupation of Hami. It was then that the Western Countries are stated to have first entered again into relations with the Chinese empire after an interruption of sixty-five years (A.D. 9-73).

Cf. Wylie, J. Anthrop. Inst., x. pp. 21 sq. ; Chavannes, T'oung-pao, 1907, p. 169.