Indian "secular" historians may distort history, but the wikipedia confirms that the barbarians plundered the region merely to spread their stupid religion. They conquered the regions in the name of Islam:
"In the 7th century AD, Arab armies brought the new religion of Islam to the region but were unable to succeed in fully converting the population. In 870 AD, Yaqub ibn Layth Saffari, a local ruler of the Saffarid dynasty in Seistan, conquered Kandahar and the rest of the nearby regions in the name of Islam. Dupree writes:
... 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%u2019s apprentice Yaqub ibn Layth Saffari, came forth from his capital at Zaranj in 870 AD and marched through Bost, Kandahar, Ghazni, Kabul, Bamiyan, Balkh and Herat, conquering in the name of Islam ..."
