The Mohammedans meanwhile had their hands full in reducing disorders in Transcaspia, and their ill-success accounts for the perpetual changes made in the leaders of their troops. The Turks, indeed, were yearly growing in power and insolence. Muslim ibn Sa`īd suffered a series of defeats at their hands which culminated in an utter rout of the Mohammedan army, the survivors escaping with difficulty across the river of Balkh. In A.H. 105 (723) Yezīd II. died, and was succeeded by his brother Hishām, who at once appointed Khalid ibn `Abdullah al-Kasrī governor of the two `Irāks, while he despatched Khālid’s brother Asad with a powerful army to bring the Turks into subjection. He failed as miserably as his predecessor; for thrice in successive years he crossed the Balkh River and marched into Soghdiana, as often to retreat with severe losses. Enraged by his continued misfortunes, he called together his generals and roundly accused them of being the cause. He then had them stripped, bastinadoed, and shaved, and sent them in chains to his brother Khālid.[151] This outrageous behaviour disgusted the Caliph, who dismissed Asad and gave the command of the Eastern army to Ashras ibn `Abdullah.[152] The new general was held in high esteem by his followers, and received the title of “the Perfect.” He made great efforts to induce the Christians of Central Asia to embrace Islām, by promising them exemption from the capitation tax. He appears, however, not to have abided by his word, but to have reimposed the tax, with the result that many of the recent converts rose in rebellion and attached themselves to the Khākān. But Ashras, too, met with a crushing defeat at the hands of the Turks, and was consequently recalled. In the person of his successor, Junayd ibn `Abd er-Rahmān,[153] we find a man more fit for supreme command than those who had preceded him. In his first engagement with the Turks he defeated the Khākān with a force of 170,000 men, of whom the Musulmans killed about 3000.[154] Junayd then retired across the Balkh River to Merv, where he wintered.
In the following spring he crossed the Oxus with his whole force, and on gaining the right bank divided it into three corps. The first, consisting of 10,000 men, he sent under Saura ibn el-Hurr to occupy Samarkand. The second division was ordered to Tokhāristān under Omāra ibn Horaym, who quickly reduced the whole province; while Junayd himself took command of the remainder.