This disaster, which is known as the “Day of Thirst,” marks a period in the history of the Arab conquests. It was practically the last aggressive expedition of the Arabs into Transoxania for fifteen years, but of much greater importance was the blow which it struck at Arab prestige. The rôles were reversed; from now onwards the Arabs found themselves on the defensive and were gradually ousted from almost every district across the Oxus. No wonder, therefore, that the memory of the “Day of Thirst” rankled even long after it had been avenged[78]. According to the Arab tradition, the Türgesh armies were led on this occasion not by Su-Lu himself, but by one of his sons. Unfortunately the accounts of Su-Lu in such Chinese works as have been translated are silent on his Western expeditions, and the Arab historians are our only authorities. The immediate result of the Arab defeat, not only in _S_ughd but in _T_ukhāristān and the southern basin as well, was to stiffen the attitude of passive resistance to the Arabs to the point at which it only needed active support to break into a general conflagration. From this time, if not before, the subject princes regarded the Türgesh as the agents of their deliverance, commissioned by China in response to the urgent entreaties they had addressed to the Emperor for aid in their struggle. We find this actually expressed in a letter sent three years later by the Jabghu of _T_ukhāristān, which is, in Chavannes’ words “but one long cry of distress”[79]. “I am loaded with heavy taxation by the Arabs; in truth, their oppression and our misery are extreme. If I do not obtain the help of the (Chinese) Kagan ... my kingdom will certainly be destroyed and dismembered.... I have been told that the Celestial Kagan has given this order to the Kagan of the Türgesh: To you I delegate the affairs of the Far West; you must at once send soldiers to drive out the Arabs.” The point of view here expressed is of course that of the ruling princes, whose resentment at the curtailment of their authority is understandable. Besides making allowance for some natural exaggeration, it would be dangerous to assume that this was as yet fully shared by the people. In all probability, if we may judge from historical analogies, there was also a pro-Arab party in Sogdiana, who felt that the best interests of the country lay, not in an opposition whose final issue could scarcely be in doubt, but in co-operation with their new masters as far as was possible. The tragedy of the Arab administration was that by alternately giving and refusing co-operation on its side, it drove its supporters in the end to make common cause with its opponents.