battle of Qohest?n in 651-52 AD, trying to block their advance on Nish?pur, but they were defeated
When the Arab armies appeared in Khor?s?n in the 650s AD, Her?t was counted among the twelve capital towns of the Sasanian Empire. The Arab army under the general command of Ahnaf ibn Qais in its conquest of Khor?s?n in 652 seems to have avoided Her?t, but it can be assumed that the city submitted to the Arabs, since shortly afterwards an Arab governor is mentioned there. A treaty was drawn in which the regions of B?dghis and Bushanj were included. As did many other places in Khor?s?n, Her?t rebelled and had to be re-conquered several times. In 702 AD Yzid ibn al-Muhallab defeated certain Arab rebels, followers of Ibn al-Ash'ath, and forced them out of Herat. The city was the scene of conflicts between different groups of Muslims and Arab tribes in the disorders leading to the establishment of the Abbasid Caliphate. Herat was also a centre of the followers of Ustadh Sis.
In 870 AD, Yaqub ibn Layth Saffari, a local ruler of the Saffarid dynasty conquered Herat and the rest of the nearby regions in the name of Islam.
...Arab armies carrying the banner of Islam came out of the west to defeat the Sasanians in 642 AD and then they marched with confidence to the east. On the western periphery of the Afghan area the princes of Herat and Seistan gave way to rule by Arab governors but in the east, in the mountains, cities submitted only to rise in revolt and the hastily converted returned to their old beliefs once the armies passed. The harshness and avariciousness of Arab rule produced such unrest, however, that once the waning power of the Caliphate became apparent, native rulers once again established themselves independent. Among these the Saffarids of Seistan shone briefly in the Afghan area. The fanatic founder of this dynasty, the coppersmith�s apprentice Yaqub ibn Layth Saffari, came forth from his capital at Zaranj in 870 AD and marched through
