Abu Muslim and the Establishment of Abbasid Caliphate
It was out of these independent movements that the next strong Muslim dynasty to rule the Islamic Empire was born. As mentioned before, the ever increasing pressure of the Umayyad Caliphs and their undeniable corruption sparked anti Arabic movements in the former Sasanian territories. These initiatives were more or less unsuccessful in achieving their goals, especially the ones who rejected the new religion and wanted to demanded a return to the situation under the Sasanian rule.
One exception to this rule was the movement led by Abu Muslim,
son of a converted Iranian from Khorasan. Abu Muslim was initially
a mojahed , but he later realised the corruption of the Umayyad Caliphs,
and established an opposition in support of the claims of one family to
the Caliphate. This family, descendants of Prophet Mohammad's uncle,
Abbas, were among the few strong claimants to the Caliphate and
serious enemies of the Umayyad dynasty. With their moral support
and the backing of his troops, Abu Muslim marched towards the Umayyad capital,
Damascus. He would have been more successful if a weak Umayyad caliph,
someone like Hesham II, was on the throne. But at the time,
Marvan II Hammar, a seasoned soldier, was the ruling Umayyad Caliph.
Despite this considerable disadvantage, the unanimous hatred of the Muslim
population towards the Umayyad dynasty eventually leaned the heavier side
of the scale towards Abu Muslim. Marvan II was set to flee and the
Abbasid claimant, Abdullah Al Saffah, was installed as the new Caliph.
Al Mansour, Haroun, and the Abbasid Empire
Abbasid Caliphate was the strongest, most successful, and the most famous of all Islamic dynasties, which lasted for over 500 years. Although at times on the end of their strength and ruling only territories as small as a city, the Abbasids always kept their role as the supreme rulers of the Muslim lands. Until their total destruction by the Mongol ruler, Hologu Khan, all of the Muslim kings claimed their authority from the Abbasid Caliphs.
Since the Abbasid rule over Iran did not last very long and dealing with their history requires a space far more than the one present, I shall only mention the highlights of their rule as far as it concerns Iran. The history of Abbasids has been well studied by many scholars and the curious reader should consult those well written works.
A defining characteristic of the Abbasid Caliphate was their obvious borrowings from the Sasanian Emperors. The strong ties of the Abbasid Caliphs to Iran and their employment of Iranian ministers such as the Barmaki family, meant adoption of Sasanian standards of government by the new dynasty. Abbasids increasingly tended towards construction of glorious monuments and cities with Sasanian influenced architectures. Their taste for luxury eventually gave rise to an Empire, built upon the ashes of the old, humble caliphate desired by people like Abu Bakr, Omar, and Ali.
The first Abbasid caliph, Al Saffah, was replaced by his brother, Mansour Al Dawanighi. Mansour was a ruthless and Machiavellian ruler. His first act as the caliph was to exterminate his enemies and potential competitors, among them Abu Muslim himself. Abu Muslim's popularity among the people and especially Iranians was an alarming sign for Mansour who had always mindful of him. So, Abu Muslim was put to death by the person whom he had helped reach the power.
Mansour's early acts as the caliph were all in line of establishing his rule over the whole empire. At the time, Spain and North Africa had succeeded from the rest of the empire and were established as the Caliphate of Cordoba by an Umayyad prince, Abdolrahman I. Mansour needed to make sure that the rest of the territories would stay under his rule. He ordered the construction of a new capital just south of Ctesiphon. The new city, built over an old Sasanian trading centre called Bagdat, was to become the most glorious city in the Muslim world for the next thousand years. Baghdad (the Arabic pronunciation) was constructed based on the models of Ctesiphon and other Sasanian cities. From there, Mansour started organising his empire and extinguishing all opposition.
The two caliphs who followed Mansour, Al Mahdi and Al Hadi, continued his policies by organising the empire and establishing institutions to control the trade, defence, and justice. They also followed Mansour's plans of constructing new cities and expanding the existing ones. They also started the construction of libraries and centres of education. Muslim scientists, many of them from Iranian lands, headed towards Baghdad to teach and learn in the houses of knowledge (universities) and read books in the libraries. This was the start of the Golden Era of Islam.
Probably the most famous Abbasid caliph, and the one best known by the westerners, was Abu Jafar Haroun Al-Rashid. Haroun, as he was commonly known, was the picture of a Medieval Muslim ruler. He presided over a flourishing empire, which unlike its European contemporaries, was on the height of its power and glory. It was under Haroun that great scientists like Zakaria Razi (Al Rhazes) and Jaber ibn Hayyan started teaching in universities and establishing institutions such as hospitals that later were adopted by Europeans. The books of Greek, Roman, and Iranian scientists were translated into Arabic and Muslim scholars read and added to this knowledge. They first established what is today called "the scientific system," analysing and reasoning the matters. At the height of their intellectual achievements, Muslim scholars questioned and reasoned subjects such as the existence of the world and philosophy of life, without the fears of Inquisition and excommunication that their European counterparts had to consider.
In a political sense, Haroun kept a tight grip over his empire and was
known as a heavy handed ruler. His famous ministers and advisers,
the Barmaki brothers from Bactria (Balkh), helped him become
the strongest ruler Muslim world had ever known, but they were put to death
when their influence was thought to be above the one of Haroun himself.
His strong rule did have its negative outcomes, most bluntly in fragmentation
of the empire which started immediately following his death. His
rule was opposed by many, among them the claimants to the caliphate from
the House of Ali. These leaders of the Shi'ite movement were
the much feared enemies of the Abbasids and although divided among themselves,
they presented a united threat to the Abbasids. Haroun's rule coincided
with the leadership of Jafar Al Sadegh over the Shi'it movement.
Al Sadegh was known for his strong and uncompromising beliefs, and he was
also an accredited scholar with people such as Jaber ibn Hayyan as his
student. Haroun was forced to deal violently with such movements
and in case of Al Sadegh, to murder the leader. This policy, although
successful at the time, proved to be defeating the purpose in the long
run, as it provided the movement with yet another reason to resist the
Abbasid power. Haroun died after a long and glorious rule and left his
empire for his sons who proved unworthy of their father.
Ma'moun and Motawakkel and the first Iranian Kingdoms
Haroun's two eldest sons, Mohammad Al Amin and Abdullah Al Mamoun, were the obvious choices to replace their father, but Haroun died without naming either one as his definite successor. Ma'moun, whose mother was Iranian, moved his seat to the city of Tous in Khorasan, and tried to take advantage of his supporters among Iranians. Amin, on the other hand, stayed in Baghdad and tried to raise an army to fight his brother. The war between the brothers was the first sign of a weakening central government, providing an opportunity for the local powers to gain their independence.
In order to take full advantage of his popularity among Iranians, Ma'moun even offered to make Al Reza (the leader of the Shi'it movement and a popular character in Iran) his heir apparent. This trick worked under the constant pressure of Ma'moun on Al Reza. Eventually, the disagreement between the uncompromising Reza and the ruthless caliph ended up in the poisoning of the Shi'ite ruler and end of Ma'moun's venture in attracting Shi'it support. At the end, Amin was defeated and Ma'moun became the sole caliph of a deeply scarred and divided empire. He was soon replaced by his younger brother Al Mo'tasam, and his son Al Mutawakkil the last strong Abbasid ruler.
Although as heavy handed as his father Haroun and as determined as Ma'moun in keeping his empire together, Motawakkel could not stop the waves of independence around his empire. All over the Abbasid Caliphate, local rulers and military strongmen were declaring their independence and establishing their own petty states. In Iran, Taher ibn Abdollah, a commander of the Abbasid army in Khorasan, declared himself king and established the first post Islamic Iranian kingdom. He was soon followed by other rebels who established their rule all over the country. One of them, Mazyar of the Qaren family, succeeded in carving out a large part of central Iran from the Abbasid territory, but he was betrayed by his followers to the Abbasids. Another famous rebellion, that of Babak, was founded in Azerbaijan. Babak, probably a Mazdaki faithful, gathered a group of highly trained soldiers in his castle near Ardebil and declared war on the Muslim ruler of Azerbaijan. Soon he was joined by many other desperate outlaws who strengthened his Red Garments army. Babak's territory expanded at an unexpected rate and his popularity soared among the oppressed people. Feeling the eventual danger, Abbasids were forced to send large armies to fight Babak, and although defeated many times by him, the Abbasid army finally succeeded in capturing and killing Babak. This was not an end for the Iranian opposition who continued their fight against the Arab domination. In the end, they were so successful that in 4th century AD, an Iranian commander was installing and deposing caliphs. The policy of dictatorship had backfired, caliphate was no more!