Arabs occupied Persia in 642 (during the Caliphate of Uthman, 644–656 AD). Attracted by the grandeur and wealth of Balkh, they attacked it in 645 AD. It was only in 653 when Arab commander al-Ahnaf raided the town again and compelled it to pay tribute. The Arab hold over the town, however, remained tenuous. The area was brought under Arab control only after it was reconquered by Muawiya in 663 AD. Prof. Upasak describes the effect of this conquest in these words: "The Arabs plundered the town and killed the people indiscriminately. It is said that they raided the famous Buddhist shrine of Nava-Vihara, which the Arab historians call 'Nava Bahara' and describe it as one of the magnificent places, which comprised a range of 360 cells around the high stupas'. They plundered the gems and jewels that were studded on many images and stupas and took away the wealth accumulated in the Vihara but probably did no considerable harm to other monastic buildings or to the monks residing there".