The Abbasid Dynasty, known to its supporters as the ‘blessed dynasty’, which imposed its authority on the Islamic empire in 132/750, claimed to inaugurate a new era of justice, piety and happiness. The dynasty ruled the Islamic Caliphate from 750 to 1258 AD, making it one of the longest and most influential Islamic dynasties. For most of its early history, it was the largest empire in the world, and this meant that it had contact with distant neighbors such as the Chinese and Indians in the East, and the Byzantines in the West, allowing it to adopt and synthesize ideas from these cultures.The replacement of the Umayyads by the Abbasids in the leadership of the Islamic community was more than a mere change of dynasty. It was a revolution in the history of Islam, as important a turning point as the French and Russian Revolutions in the history of the west. The Umayyad administration (661-750) of the Islamic Empire created serious grievances among various political, religious, social and ethnic groups. Their monopoly of power denied other people important administrative positions and the accompanying privileges and benefits.The Umayyads favored Syrian Arabs over other Muslims and treated mawali, newly converted Muslims, as second class citizens. The most numerous group of mawali were the Persians, who lived side by side with Arabs in the east who were angry at the favor shown to Syrian Arabs. Together, they were ripe for rebellion. Other Muslims were angry with the Umayyads for turning the caliphate into a hereditary dynasty, for their over-dependence upon the bureaucracy of the preceding Byzantine Empire, for levying taxes forbidden by the Qur’an, and for their ethnocentric policies.Some believed that a single family should not hold power, while Shiites believed that true authority belonged to the family of the Prophet Muhammad through his son-in-law Ali, and the Umayyads were not part of Muhammad’s family. The Umayyads were accused by several religious groups of having a weak commitment to Islam. It will be remember that the Abbasid originally came to power by utilizing the discontent of the different segments of the empire such as the shi’is, the kharijites, the religiously orthodox, the Persian and other malcontents.All these various groups who were angry with the Umayyads united under the Abbasids, who began a rebellion against the Umayyads in Persia. The Abbasids built a coalition of Persian mawali, Eastern Arabs, and Shiites. The Abbasids were able to gain Shiite support because they claimed descent from Muhammad through Muhammad’s uncle Abbas. Their descent from Muhammad was not through Ali, as Shiites would have preferred, but Shiites still considered the Abbasids better than the Umayyads. A Persian general, Abu Muslim, who supported Abbasid claims to power, led the Abbasid armies.His victories allowed the Abbasid leader Abul `Abbas al-Saffah to enter the Shiite-dominated city of Kufa in 748 and declare himself caliph. In 750, the army of Abu Muslim and al-Saffah faced the Umayyad Caliph Marwan II at the Battle of the Zab near the Tigris River. Marwan II was defeated, fled, and was killed. As-Saffah captured Damascus and slaughtered the remaining members of the Umayyad family (except for one, Abd al-Rahman, who escaped to Spain and continued the Umayyad Dynasty there). The Abbasids were the new rulers of the caliphate.The ‘Abbasid revolution marked the end of the Arab empire and beginning of an integrated Islamic society in which the underprivileged mawali- (non-Arab clients) played a crucial role in the evolution of a common culture based on Islam and the Arabic language. In 1902 Wellhausen wrote: “The ‘Abbasids called their government the dawlah, i. e. , the new era. The revolution affected at this time was indeed prodigious. ” The Abbasids had led a revolution against the unpopular policies of the Umayyads, but those who expected major change were disappointed. Under the second Abbasid Caliph, al-Mansur (r. 54–775), it became clear that much of the Umayyad past would be continued. The Abbasids maintained the hereditary control of the caliphate, forming a new dynasty. The alliance with the Shiites was short lived, and the Abbasids became champions of Sunni orthodoxy, upholding the authority of their family over that of Ali, and continuing the subjugation of the Shiites. Even Abu Muslim, the popular leader who more than any other single individual was the architect of the Abbasid victory, was put to death by the second Abbasid Caliph, Al- Mansur. However, the Abbasids did prove loyal to their Persian mawali allies. In act, Abbasid culture would come to be dominated by the legacy of Persian civilization. The Abbasid court was heavily influenced by Persian customs, and members of the powerful Persian Barmakid family acted as the advisers of the caliphs and rivaled them in wealth and power. One of the earliest and most important changes the Abbasids made was to move the capital of the Islamic empire from the old Umayyad power base of Damascus to a new city—Baghdad. Baghdad was founded in 762 by al-Mansur on the banks of the Tigris River. The city was round in shape, and designed from the beginning to be a great capital and the center of the Islamic world.Baghdad grew quickly with encouragement from the Abbasid state, and it was soon the largest city in the world. At Baghdad, the Persian culture that the Umayyads had attempted to suppress was now allowed to thrive. Art, poetry, and science flourished. The Abbasids learned from the Chinese (allegedly from Chinese soldiers captured in battle) the art of making paper. Cheap and durable, paper became an important material for spreading literature and knowledge. Abbasid administration was a development of that of the late Umayyads, and Mansur openly admitted his great debt to the Umayyad Caliph Hisham in the organization of the state.It no longer based on racial administration and exclusiveness. A new position that of the vizier (wazir) was also established to delegate central authority, he was next to the Caliph. This office was an Abbasid innovation, possibly of Persian origin. Eventually, this meant that many Abbasid caliphs were relegated to a more ceremonial role than under the Umayyads, as the viziers began to exert greater influence, and the role of the old Arab aristocracy was slowly replaced by a Persian bureaucracy.A dictum of the Abbasids said that he who obeys the vazir has obeyed the caliph and he who obeys the caliph has obeyed God! One of the most important departments of the administration was the Department of Taxation. A significant feature of the Abbasid government was the postal department, of which was called Sahib al-barid. Interestingly enough, one of the functions of the post Office was intelligence service. Perhaps the only difference was that the Abbasid chief of the intelligence used a large number of old women in his service. Other departments of administration were audit, chancery and police.One of the functionaries of the Police Department was the muhtasib, who was in charge of public morals and religious observance. In the Army, the Arab militia was no longer important and the pensions paid to the Arabs were gradually discontinued except for regular serving soldiers, the all-Arab forces which had directly established the authority of the conquering people were replaced by a professional army and by the militia of the Persian dihqans supporting the dynasty who gradually supplanted the Arab tribal levies, thereafter recruited only for major campaigns.The rise of the Abbasids also greatly enriched Islamic literature as well as the natural sciences. Mathematics, astronomy and chemistry all advanced greatly during that period, mostly due to efforts by Muslim Persians in those respective fields. The openness of the Abbasid community allowed for new ideas and new methods of production to overcome their Arab counterparts and would reshape the present industries into something more efficient and eventually produce more wealth. The fifth caliph of the Abbasid dynasty, Harun al-Rashid (r. 86–809), is remembered as one of history’s greatest patrons of the arts and sciences. Under his rule, Baghdad became the world’s most important center for science, philosophy, medicine, and education. The massive size of the caliphate meant that it had contact and shared borders with many distant empires, so scholars at Baghdad could collect, translate, and expand upon the knowledge of other civilizations, such as the Egyptians, Persians, Indians, Chinese, Greeks, Romans, and Byzantines.The successors of Harun al-Rashid, especially his son al-Ma’mun (r. 813–833), continued his policies of supporting artists, scientists, and scholars. Al-Ma’mun founded the Bayt al-Hikma, the House of Wisdom, in Baghdad. A library, an institute for translators, and in many ways an early form of university, the House of Wisdom hosted Muslim and non-Muslim scholars who sought to translate and gather the cumulative knowledge of human history in one place, and in one language—Arabic. At the House of Wisdom, important ideas from around the world came together.The introduction of Indian numerals, which have become standard in the Islamic and Western worlds, greatly aided in mathematics and scientific discovery. Scholars such as Al-Kindi revolutionized mathematics and synthesized Greek philosophy with Islamic thought. Al-Biruni and Abu Nasr Mansur—among many other scholars—made important contributions to geometry and astronomy. Al-Khwarizmi, expanding upon Greek mathematical concepts, developed Algebra (the word “algorithm” is a corruption of his name).Ibn al-Haytham made important contributions to the field of optics, and is generally held to have developed the concept of the scientific method. A number of very practical innovations took place, especially in the field of agriculture. Improved methods of irrigation allowed more land to be cultivated, and new types of mills and turbines were used to reduce the need for labor (though slavery was still very common in both the countryside and cities).The Revolution gave the peasants greater possession rights and a more equitable system of tax assessment, based on a percentage of the crop, instead of a fixed rate, as previously. Crops and farming techniques were adopted from far-flung neighboring cultures. Hence, under the Abbasids, the Arab Empire was quickly metamorphosed into an international Muslim Empire, and the caliph became an omnipotent despot surrounded by imperial pomp and circumstance alien to the native Arab ideas-no doubt shared by the Prophet himself-of equality and simplicity.Soon enough absolute power and unlimited luxury corrupted the moral fiber of the dynasty, and the later Abbasid caliphs progressively became mere figureheads manipulated at will by non- Arab ruling provincial vassals, who were to all intents and purposes autonomous sovereigns over their own fiefs. The dynasty finally ceased when the Mongols stormed Baghdad in the year I258 and put the last Abbasid caliph al-Musta’sim to death.