The Arab victory at Talas in 751 was barely noticed by contemporary chroniclers, Muslim or Chinese, but the modern observer, with the advantage of hindsight, assigns to this event the exceptional historical importance it deserves. We see here what an effect a combination of geopolitical realities with an inspired militant religion can have. Distance compounded by the mighty barrier of the Tianshan and Pamir mountains made the territories to the west and northwest of Sinkiang remote and difficult of access for China, but the main cause of Muslim success and Chinese failure lay in the fact that the Celestial Empire was not fired by any comparable proselytizing zeal. In contrast, the Arabs were driven by the ideal of the jihad or Holy War, and the fact that the fruits of victory also brought the conquerors great material rewards does not diminish the catalytic role of the primary motivation. The Arabs subsequently transmitted this zeal to the converts of newly conquered Central Asian territories, so that when the caliphate began to lose its youthful vigor, the jihad was no longer led by them but by a new Iranian dynasty of Transoxania, the Samanids. Islam's penetration of these eastern marches was then consummated by the wholesale conversion of a Turkic dynasty, the Qarakhanids, with its territories and tribes joining the Dar al-Islam.

The Samanids were of Iranian stock; this underscores the fact that hence forward not Arab governors but native, at first Iranian, and later mostly Turkic, but always Muslim dynasts would rule Islamic Central Asia – except for a few special periods, the latest of which ended, for Western Turkestan, in 1991.