The Abbasid Caliphate (العبّاسيّون, ) was the third of the Islamic Caliphates of the Arab Empire. It was ruled by the Abbasid dynasty of caliphs, who built their capital in Baghdad after overthrowing the Umayyad caliphs from all but Al Andalus. It was built by the descendant of Muhammad's youngest uncle, Abbas ibn Abd al-Muttalib. It was created in Harran in 750 of the Common Era and shifted its capital in AD 762 from Harran to Baghdad. It flourished for two centuries, but slowly went into decline with the rise to power of the Turkish army it had created, the Mamluks. Within 150 years of gaining power across Persia, they were forced to cede power to local dynastic amirs who only nominally acknowledged their power, and had to cede Al Andalus to an escaped Umayyad royal and the Maghreb and Ifriqiya to independent entities such as the Aghlabids and the Fatimids. Their rule was ended in 1258, when Hulagu Khan, the Mongol conqueror, sacked Baghdad. While they continued to claim authority in religious matters from their base in Egypt, the dynasty's secular authority had ended. Descendants of the Abbasids include the al-Abbasi tribe who live northeast of Tikrit in modern-day Iraq.
The Abbasids also distinguished themselves from the Umayyads by attacking their moral character and administration in general. According to Ira Lapidus "The Abbasid revolt was supported largely by Arabs, mainly the aggrieved settlers of Marw with the addition of the Yemeni faction and their Mawali". The Abbasids also appealed to non-Arab Muslims, known as mawali, who remained outside the kinship-based society of Arab culture and were perceived of as a lower class within the Umayyad empire. Muhammad ibn 'Ali, a great-grandson of Abbas, began to campaign for the return of power to the family of Muhammad, the Hashimites, in Persia during the reign of Umar II, Muhammad ibn Ali.
During the reign of Marwan II, this opposition culminated in the rebellion of Ibrahim the Imam, the fourth in descent from Abbas. Supported by the province of Khorasan, Iran, he achieved considerable successes, but was captured in the year 747 and died in prison; some hold that he was assassinated. The quarrel was taken up by his brother Abdallah, known by the name of Abu al-'Abbas as-Saffah, who, with victory on the Greater Zab River (750), defeated the Umayyads and was proclaimed Caliph.
The Abbasids had depended heavily on the support of Persians in their overthrow of the Umayyads. Abu al-'Abbas' successor, al-Mansur, moved their capital from Damascus to the new city of Baghdad and welcomed non-Arab Muslims to their court. While this helped integrate Arab and Persian cultures, it alienated many of their Arab supporters, particularly the Khorasanian Arabs who had supported them in their battles against the Umayyads.
These fissures in their support led to immediate problems. The Umayyads, while out of power, were not destroyed. The only surviving member of the Umayyad royal family, which had been all but annihilated, ultimately made his way to Spain where he established himself as an independent Emir (Abd ar-Rahman I, 756). In 929, Abd ar-Rahman III assumed the title of Caliph, establishing Al Andalus from Córdoba as a rival to Baghdad as the legitimate capital of the Islamic Empire.
The Islamic Golden Age was inaugurated by the middle of the 8th century by the ascension of the Abbasid Caliphate and the transfer of the capital from Damascus to Baghdad. The Abbassids were influenced by the Qur'anic injunctions and hadith such as "the ink of scientists is more holy then the blood of martyrs" stressing the value of knowledge. During this period the Muslim world became the unrivaled intellectual center for science, philosophy, medicine and education as the Abbasids championed the cause of knowledge and established a "House of Wisdom" in Baghdad; where both Muslim and non-Muslim scholars sought to translate and gather all the world's knowledge into Arabic. Many classic works of antiquity that would otherwise have been lost were translated into Arabic and later in turn translated into Turkish, Persian, Hebrew and Latin. During this period the Muslim world was a cauldron of cultures which collected, synthesized and significantly advanced the knowledge gained from the ancient Roman, Chinese, Indian, Persian, Egyptian, North African, Greek and Byzantine civilizations.
At the same time, the Abbasids faced challenges closer to home. Former supporters of the Abbasids had broken away to create a separate kingdom around Khorosan in northern Persia. Harun al-Rashid (786 – 809) turned on the Barmakids, a Persian family that had grown significantly in power within the administration of the state.
The reigns of Harun al-Rashid (786 – 809) and his successors fostered an age of great intellectual achievement. In large part, this was the result of the schismatic forces that had undermined the Umayyad regime, which relied on the assertion of the superiority of Arab culture as part of its claim to legitimacy, and the Abbasids' welcoming of support from non-Arab Muslims. It is well established that the Abbasid caliphs modeled their administration on that of the Sassanids. One Abbasid caliph is even quoted as saying:
A number of medieval thinkers and scientists living under Islamic rule played a role in transmitting Islamic science to the Christian West. They contributed to making Aristotle known in Christian Europe. In addition, the period saw the recovery of much of the Alexandrian mathematical, geometric and astronomical knowledge, such as that of Euclid and Claudius Ptolemy. These recovered mathematical methods were later enhanced and developed much further by other Islamic scholars, notably by Al-Biruni and Abu Nasr Mansur.
Algebra was also pioneered by Muhammad ibn Mūsā al-Khwārizmī during this time in his landmark text, Kitab al-Jabr wa-l-Muqabala, from which the term algebra is derived. He is thus considered to be the father of algebra. The terms algorism and algorithm are also derived from the name of al-Khwarizmi, who was responsible for introducing the Arabic numerals and Hindu-Arabic numeral system beyond the Indian subcontinent.
Ibn al-Haytham (Alhazen) developed an early scientific method was developed by in his Book of Optics (1021). The most important development of the scientific method was the use of experiments to distinguish between competing scientific theories set within a generally empirical orientation, which began among Muslim scientists. Ibn al-Haytham is also regarded as the father of optics, especially for his empirical proof of the intromission theory of light. Bradley Steffens described Ibn al-Haytham as the "first scientist for his development of scientific method.
Medicine in medieval Islam was an area of science that advanced particularly during the Abbasids' reign. During the ninth century, Baghdad contained over 800 doctors, and great discoveries in the understanding of anatomy and diseases were made. The clinical distinction between measles and smallpox was discovered during this time. Famous scientist Ibn Sina (known to the West as Avicenna) produced treatises and works that summarized the vast amount of knowledge that scientists had accumulated, and is often known as the father of modern medicine for his encyclopedias, The Canon of Medicine and The Book of Healing. The work of him and many others directly influenced the research of European scientists during the Renaissance and even later.
Astronomy in medieval Islam was advanced by Al-Battani, who improved the precision of the measurement of the precession of the earth's axis. The corrections made to the geocentric model by al-Battani, Averroes, Nasir al-Din al-Tusi, Mo'ayyeduddin Urdi and Ibn al-Shatir were later incorporated into the Copernican heliocentric model. The astrolabe, though originally developed by the Greeks, was perfected by Islamic astronomers and engineers, and was subsequently brought to Europe.
Muslim chemists and alchemists played an important role in the foundation of modern chemistry. Scholars such as Will Durant and Alexander von Humboldt regard Muslim chemists to be the founders of chemistry. In particular, Geber (Jabir ibn Hayyan) is considered the "father of chemistry". The works of Arab chemists influenced Roger Bacon (who introduced the empirical method to Europe, strongly influenced by his reading of Arabic writers), Isaac Newton, among many others. A number of chemical processes such as distillation techniques and the production of alcohol were developed in the Muslim world and then spread to Europe.
The most well known fiction from the Islamic world was The Book of One Thousand and One Nights (Arabian Nights), which was a compilation of many earlier folk tales. The epic took form in the 10th century and reached its final form by the 14th century; the number and type of tales have varied from one manuscript to another. All Arabian fantasy tales were often called "Arabian Nights" when translated into English, regardless of whether they appeared in The Book of One Thousand and One Nights. This epic has been influential in the West since it was translated in the 18th century, first by Antoine Galland. Many imitations were written, especially in France. Various characters from this epic have themselves become cultural icons in Western culture, such as Aladdin, Sinbad and Ali Baba.
A famous example of Arabic poetry and Persian poetry on romance (love) is Layla and Majnun, dating back to the Umayyad era in the 7th century. It is a tragic story of undying love much like the later Romeo and Juliet, which was itself said to have been inspired by a Latin version of Layli and Majnun to an extent.
One of the common definitions for "Islamic philosophy" is "the style of philosophy produced within the framework of Islamic culture." Islamic philosophy, in this definition is neither necessarily concerned with religious issues, nor is exclusively produced by Muslims. Their works on Aristotle was a key step in the transmission of learning from ancient Greeks to the Islamic world and the West. They often corrected the philosopher, encouraging a lively debate in the spirit of ijtihad. They also wrote influential original philosophical works, and their thinking was incorporated into Christian philosophy during the Middle Ages, notably by Thomas Aquinas.
Three speculative thinkers, al-Kindi, al-Farabi, and Avicenna, combined Aristotelianism and Neoplatonism with other ideas introduced through Islam, and Avicennism was later established as a result. Other influential Muslim philosophers in the Caliphates include al-Jahiz, a pioneer in evolutionary thought, and Ibn al-Haytham (Alhacen), a pioneer of phenomenology and the philosophy of science and a critic of Aristotelian physics and Aristotle's concept of place (topos).
In technology, the Muslim world adopted papermaking from China and further advanced the technology with their invention of papermills many centuries before paper was known in the West. The knowledge of gunpowder was also transmitted from China via Islamic countries, where the formulas for pure potassium nitrate and an explosive gunpowder effect were first developed.
Advances were made in irrigation and farming, using new technology such as the windmill. Crops such as almonds and citrus fruit were brought to Europe through al-Andalus, and sugar cultivation was gradually adopted by the Europeans. Arab merchants dominated trade in the Indian Ocean until the arrival of the Portuguese in the 16th century. Hormuz was an important center for this trade. There was also a dense network of trade routes in the Mediterranean, along which Muslim countries traded with each other and with European powers such as Venice, Genoa and Catalonia. The Silk Road crossing Central Asia passed through Muslim states between China and Europe.
Muslim engineers in the Islamic world made a number of innovative industrial uses of hydropower, and early industrial uses of tidal power, wind power, steam power, fossil fuels such as petroleum, and early large factory complexes (tiraz in Arabic). The industrial uses of watermills in the Islamic world date back to the 7th century, while horizontal-wheeled and vertical-wheeled water mills were both in widespread use since at least the 9th century. A variety of industrial mills were being employed in the Islamic world, including early fulling mills, gristmills, hullers, paper mills, sawmills, shipmills, stamp mills, steel mills, sugar mills, tide mills and windmills. By the 11th century, every province throughout the Islamic world had these industrial mills in operation, from al-Andalus and North Africa to the Middle East and Central Asia. Muslim engineers also invented crankshafts and water turbines, employed gears in mills and water-raising machines, and pioneered the use of dams as a source of water power, used to provide additional power to watermills and water-raising machines. Such advances made it possible for many industrial tasks that were previously driven by manual labour in ancient times to be mechanized and driven by machinery instead in the medieval Islamic world. The transfer of these technologies to medieval Europe had an influence on the Industrial Revolution.
A number of industries were generated due to the Muslim Agricultural Revolution, including early industries for agribusiness, astronomical instruments, ceramics, chemicals, distillation technologies, clocks, glass, mechanical hydropowered and wind powered machinery, matting, mosaics, pulp and paper, perfumery, petroleum, pharmaceuticals, rope-making, shipping, shipbuilding, silk, sugar, textiles, water, weapons, and the mining of minerals such as sulfur, ammonia, lead and iron. Early large factory complexes (tiraz) were built for many of these industries, and knowledge of these industries were later transmitted to medieval Europe, especially during the Latin translations of the 12th century, as well as before and after. For example, the first glass factories in Europe were founded in the 11th century by Egyptian craftsmen in Greece. The agricultural and handicraft industries also experienced high levels of growth during this period.
All these autonomous provinces slowly took on the characteristic of de facto states with hereditary rulers, armies, and revenues and operated under only nominal caliphal suzeranity, which may not necessarily be reflected by any contribution to the treasury. The eventual rise of the Ghaznavid Empire and the Seljuks to displace all these factions marked the end of Abbasid political dominion over the area.
The Mamluk army, though often viewed negatively, both helped and hurt the caliphate. Early on, it provided the government with a stable force to address domestic and foreign problems. However, creation of this foreign army and al-Mu'tasim's transfer of the capital from Baghdad to Samarra created a division between the caliphate and the peoples they claimed to rule. In addition, the power of the Mamluks steadily grew until al-Radi (934 – 941) was constrained to hand over most of the royal functions to Mahommed bin Raik. In the following years, the Buwayhids, who were Shi'ites, seized power over Baghdad, ruling central Iraq for more than a century.