In the mid-eighth century a revolution began against the Ummayad Caliphate. The Ummayads managed to suppress many of these uprising but with every one that was put down, ten more would occur throughout the Caliphate. There were several reasons for the displeasure and anger towards the Ummayads. The racism against the non-Arab Muslims lost the Ummayads much support as this new multi-ethnic empire consisted largely of non-Arabs. But the most important reason may have been the events of Karbala. The slaying of the Prophets grandson was something that the Ummayad could never recover from. In the eyes of many throughout the empire, the Ummayad had lost the right to rule and it was only a matter of time before they would be overthrown.

The black standard of the Abbasid revolution and the Abbasid dynasty, the opposite of the Umayyad white standard

The above video is a great summary about the Abbasid Revolution.

Baghdad

To start, one of the greatest achievements of the Abbasid Caliphate was the development of Baghdad. The Abbasid knew that they must move the rule away from Damascus, the center of power of the Ummayads. Under the rule of the Abbasids, a collection of small villages was turned into one of the greatest cities on the face of the Earth. Caliph Al-Mansur would order the construction of a new capital and this great responsiblility would be given to the Barmakids, a Persian influential family that would become one of the most powerful families within the Caliphate under the Abbasid rule. This stood testament to the change in the new Caliphate. No longer would the non-Arabs be second class citizens.

An artists rendition of what he imagined the city to have been like in it’s glory.

The greatest engineers were assembled to plan this city that would be the heart of the Islamic world for centuries to come. It was decided that it would be built beside the river Tigris where water would be in abundance. Unlike the majority of the cities of it’s time Baghdad was to be a round city surrounded by canals and an extensive irrigation system. Around 100,000 of the best workers were gathered to build this magical city. When it was complete, the city stood as a testament to the Abbasid power and the new age.

The planned round city of Baghdad

The ancient city of Baghdad

Ending racism

As I mentioned before the society under the Umayyad dynasty was divided into groups based on racism. The non-Arab Muslims were second class citizens and discriminated against. This went against the very teachings of Islam and the Prophet. As the Caliphate expanded and grew, the numbers of non-Arabs outgrew the Arabs. This worried the Ummayad elite Arabs. They saw Islam as something that belonged to them, the Arabs. The Arabs would live in well-protected garrisoned cities where the non-Arabs were not allowed to live. The non-Arabs would not be allowed to hold any high ranking government or military position. Even interracial marriages were not allowed with the exception that the man was an Arab and the woman a non-Arab. The Ummayads had discarded the very basics of Islam and replaced it with pride and arrogance.

The non-Arabs expressed their anger by supporting the Abbasid revolution and overthrowing the Ummayad for a more fair dynasty that would treat them equally. The Abbasid would improve the status of the non-Arab Muslims. Finally they would participate in the military and governance at all levels.

The anti-Persian sentiment was very common under the Ummayad Caliphate. At the forefront of this was the forceful Arabization of Persia. A move that would spectacularly fail. The Abbasid however would incorporate the Persians into every level of the society. This would result in Islam growing at an unprecedented level thoughout the Caliphate.

Not only would this increase the rate of conversion throughout the Caliphate but it would make the non-Arab Muslims far more loyal as well. This would provide a stability lacking under the Ummayads.

Winning the battle for the control of Central Asia

The silk route was the most important trading route in the entire world at the time. Whoever controlled this trade would have access to great wealth. Control over Central Asia was essential for mastery over the silk route. There were two main empires vying for control of Central Asia. These being the Tang Dynasty of China and the Abbasid Caliphate of the Middle East. Both of these empires were extremely widespread. The Central Asian front was the peripheral frontier for both of these empires.

The Tang Dynasty, the greatest power of the East

The Abbasid Caliphate, the great power from the Middle East

Both of these empires would wage a war for control of Central Asia and at the end the Abbasid Caliphate would come out on top. Central Asia would be forever free from Chinese influence and would fall under the influence of Islam.

The deciding battle in this was the Battle of the Talas River in 751 AD. This was essentially the battle between the two superpowers of their time. The Chinese forces were betrayed by the Karluk, their allies. Attacked from two sides, the Tang forces has little chance and suffered a devastating defeat. The remaining Chinese forces withdrew to regroup but a rebellion back in the Tang heartland forced them to return home and abandon Central Asia. The Abbasid now controlled Central Asia.

For a more detailed look into the the Abbasid-Tang war, watch the video below.

The technique of making paper

The war against the Tang Dynasty had a unforeseen but positive outcome. For a very long time paper making was a secret technique closely guarded by the Chinese. After winning the battle against the Tang, the Arabs captured some Chinese prisoners of war. These prisoners would exchange the secret of making paper in return for their freedom. The Arabs would use this information to build the first non-Chinese paper making mills in Baghdad. From here this technology would spread throughout the Middle East and then later into Europe as well. Paper was essential in kick-starting the golden age of the Abbasid.

The technique of making paper

Arabization

While the Umayyad Caliphate believed far more in the idea of Arab supremacy, it was actually the Abbasid Caliphate that contributed far more to Arabization of the vast regions of the Caliphate.

The Umayyads believed in the idea of Arab superiority and did not believe that non-Arabs could ever rise to the same status. Instead of mixing in with the non-Arab Muslims of the regions. The Umayyads would built forts and palaces for themselves. In these palaces the only the Arab rulers could live and non-Arabs were not allowed in. To hold any position of power or a public post, one had to be an Arab. Only an Arab could be a military commander. This prevented the natives of various regions from adapting the Arab culture and it also prevented the evolution of Arab culture. The Umayyad believed in the purity of Arab culture and blood. Mixing with the local population was frowned upon. The Umayyad rule resulted in two different Muslim groups throughout the empire. The ruling Arabs and the non-Arabs serving them, who could never rise to the same status.

The Abbasid had a different take on the whole matter. The Abbasid rose to power in Khorasan to the east. These Arabs had a different philosophy. The did not believe in living in separate forts isolated from their subjects. Instead they lived among the people. Even married into the local population. So when the Abbasid came to power things began to change.

Arabic was, like before, the language of governance. However, unlike before, now a non-Arab could hold such positions of power. This meant that local population had a reason to learn this new language, Muslim or not. The Abbasid also sparked a golden age of Islam where the Caliphate became the center of knowledge throughout the world. The language used to store all of this knowledge was Arabic and all of the scholars, despite many being non-Arabs, used Arabic to store their knowledge. The language of religion, Islam, just like before was also Arabic. Arabic, just like under the Umayyad Caliphate, was the language of nobility. The main difference was that unlike before the non-Arab new converts could also rise to the rank of nobility by adopting the Arabic language and culture. This would over time result in the Arabization of much of the Caliphate.

The Arab World today

The original Arab World

Golden Age of Islam

This golden age began in the 8th century when Caliph Harun al-Rashid inaugurated the Bayt al-Ḥikmah or the House of Wisdom in Baghdad. It would last till the 13th century with the sack of Baghdad by Hulagu Khan.

The sack of Baghdad by the Mongols. The quantity of books in the House of Wisdom is believed to have been so that the despite Nasir al-Din Tusi having rescued 400,000 manuscripts prior to the invasion, the river Tigris ran black with ink following the drowning of the books.

Baghdad was at the very heart of this golden age. In this time period, the Caliphate would become the center of knowledge in the world. Various works from the Greek, Persian, Indian, Chinese, Roman and Egyptian civilizations of the past were collected and translated into Arabic. The translations would then be stored in the House of Wisdom. In such manner knowledge from all over the world was being collected and stored in Baghdad. For any scholar of the time who wanted to learn, the Caliphate would be his best source of knowledge.

One of the earlier translated works in the House of Wisdom

For centuries Baghdad would be the place where intellectuals and scholars could meet and discuss ideas. Here all scholars would be welcome, irrespective of their religion or ethnicity. The best example of this being Hunayn ibn Ishaq, a Christian physician who was perhaps the best and leading translator in the House of Wisdom.

This age would give rise to great philosophers such as Avicenna, Al-Kindi and Al-Farabi. It gave rise to mathematicians the likes of Al-Khwarizmi, Omar Khayyam and Hasan Ibn al-Haytham. Great Astronomers such as Abd al-Rahman al-Sufi and Nasir al-Din Tusi would make great strides within their respective fields. Al-Biruni would publish his works in geometry and physics. Baghdad would also serve as home to great physicians such as Ibn al-Nafis and Hunayn ibn-Ishaq. These are just some of the names that would great contributions and help make Baghdad the heart of knowledge.

One of the greatest mathematicians in history

Quora User answer on this question provides a great insight on the works of the House of Wisdom.

The House of Wisdom

These are the main achievements off the top of my head. There were many other achievements of the Abbasid that lasted in the form of an empire for a about 500 years and as Caliphs in a divided Islamic world for another 200. The Abbasid Caliphate is responsible for much of the Arab culture in the form that it exists in today. It is also responsible for the very idea for what an Arab is and that is perhaps one of its greatest achievements.

The Abbasid Caliphate is one of the greatest and most interesting empires in history. The Abbasid overthrew the Umayyad without true fragmentation of the Empire and replaced the ruling family with relative ease. They then went on to rule for over 500 years and brought forth perhaps the greatest period of Islamic history.