worship, follow their own family law, and own property. People of the Book were not subject to certain Islamic rules, such as the prohibitions on alcohol and pork, but were subject to other restrictions. Under the Islamic state, they were exempt from military service, but were required to pay a poll tax known as . (They were, however, exempt from the required of Muslims.) They could be bureaucrats and advisors, but they could never be rulers. Later Islamic practices Under the Ummayads and Abbasids, the Islamic community was increasingly fragmented into various sects and kingdoms, each of which had its own evolving policy towards and towards conquered polytheists. Later Islamic conquests From historical evidence, it appears Tokharistan was the only area of Iran heavily colonized by Arabs, where Buddhism flourished when they arrived and the only area incorporated into the Arab empire where Sanskrit studies were pursued up to the conquest. The grandson of Barmak was the vizier of the empire and took personal interest in Sanskrit works and Indian religions. When the Barmakids were removed from power and their influence disappeared, no further translations of Sanskrit works into Arabic is known until that of Al-Biruni. With the Ghaznavids and later the Mughals, Islam also expanded further into northern India. Will Durant, in The Story of Civilization, described this as "probably the bloodiest story in history." This approach was not uniform, and different rulers adopted different strategies. The Mughal emperor Akbar, for example, was relatively tolerant towards Hindus, while his great-grandson Aurangzeb was heavily intolerant. Hindus were ultimately given the tolerated religious minority status of . The Buddhists of India were not as fortunate; although Buddhism had been in decline prior to the Muslim invasions, the destruction of monastic universities in the invasions such as Nalanda and Vikramashila were a calamity from which it never recovered. According to one Buddhist scholar, the monasteries were destroyed because they were large, fortified edifices considered threats by Muslim Turk invaders. The Almohad rulers of Muslim Spain were initially intolerant, and engaged in forced conversions; Maimonides, for example, was forced to masquerade as a Muslim and eventually flee Spain after the initial Almohad conquest. Comparative religion and anthropology of religion After the Arab conquest of the Buddhist center of Balkh, a Quranic commentator was denounced for anthropomorphism, a standard attack on those sympathetic to Buddhism. Hiwi al-Balkhi had attacked the authority of Quran and