A revolution from the east
The Abbasids took their name from al-Abbas, an uncle of the Prophet Muhammad, and they came to power by claiming to act on behalf of the Prophet’s wider family. Their revolution was prepared in secret for years. Its strongest base was Khurasan, in the north-east of the Islamic world, where Arab settlers and local converts alike had grievances against the Umayyad government in Damascus, over taxes, status and the favour shown to Syrian troops.
The movement’s military leader, Abu Muslim, raised black banners in Khurasan in 747, and his forces advanced westward. In late 749 Abu al-Abbas was proclaimed caliph in the Iraqi city of Kufa. In January or February 750 the Abbasid army defeated the last Umayyad caliph, Marwan II, at the Greater Zab river, and Damascus fell soon afterwards. Abu al-Abbas, later called al-Saffah, ruled only until 754, and his brother al-Mansur then took the throne. The early years were violent: members of the Umayyad family were hunted down, and Mansur had Abu Muslim killed in 755, apparently because he had become too powerful.
Why Baghdad
The Abbasids shifted the centre of gravity of the empire east, away from Syria and toward Iraq, where the rich farmland of the Tigris and Euphrates supported large revenues, and toward Iran, whose elites were important to the new regime. Al-Mansur began building a new capital in 762 on the west bank of the Tigris, at a point where the river and the canals linking it to the Euphrates offered water routes for trade and supply. The region had very long urban traditions: the ruins of the ancient city of Babylon lay to the south, and the Sasanian capital Ctesiphon, with its great vaulted hall known as Taq Kasra, stood just downstream. Baghdad drew on building material and, in a broad sense, on administrative traditions of those earlier Mesopotamian capitals.
The city was officially called Madinat al-Salam, the City of Peace. Its core was the Round City, a circular plan with concentric walls and four gates, with the caliph’s palace and the main mosque at the centre. It was largely complete by about 766. The design reflected security concerns as much as symbolism, since the early Abbasids faced rebellions, but the surrounding districts soon grew far beyond the walls. Markets, craft quarters and neighbourhoods filled both banks of the river, and Baghdad became one of the largest cities in the world of its day, though precise population figures are not known. Goods came from the Mediterranean, India and East Asia, tying the city to the Silk Road trade routes and to Indian Ocean shipping.
Government and the caliph’s court
Compared with the Umayyads, the Abbasid court gave greater weight to non-Arab Muslims, especially Persians. The caliph’s chief minister, the vizier, became a major figure. The Barmakid family, which came from a Buddhist-linked Central Asian background but served the Abbasids as converts, provided viziers to Harun al-Rashid (reigned 786 to 809) until they were dramatically removed from office in 803. Court ceremony took on a more remote, Persian-influenced style, and the caliph presented himself as a religious and political leader.
Political unity did not last indefinitely. By the later ninth century, governors in regions such as Egypt, Iran and Central Asia held growing independence, and the caliphs relied heavily on Turkish military slaves and soldiers. Al-Mutasim moved the court to a new city, Samarra, in 836 to separate his troops from the population of Baghdad, and the caliphs returned in the 880s. In 945 the Buyids, a family from northern Iran, took control of Baghdad, leaving the caliph as a mostly symbolic head. The dynasty finally ended in 1258, when Mongol forces under Hulagu captured and sacked the city, an event usually discussed under the Mongol conquests.
Scholarship and translation
The scholarly achievements of the early Abbasid era are famous. The caliphs and wealthy patrons paid for translations of Greek, Persian, Syriac and Sanskrit works into Arabic. Translators were frequently Christians who knew Syriac and Greek, among them Hunayn ibn Ishaq (died 873), who translated works by the physician Galen, building on the Greco-Roman medicine that Greek texts had preserved. Philosophical writings of Aristotle and Plato were translated, and thinkers such as al-Kindi engaged with them; Plato and Aristotle thus entered Arabic-language debate long before they re-entered Latin Europe. Indian numerals and astronomical tables were also studied, and Babylonian astronomy and its sexagesimal number system, a subject in its own right, left traces in the observational traditions that astronomers inherited.
The mathematician al-Khwarizmi, who worked under the caliph al-Mamun (813 to 833), wrote an influential work on solving equations, from whose title the word algebra derives. Observatories were set up in Baghdad and Damascus under al-Mamun. The adoption of paper, which spread to Baghdad in the later eighth century, made books cheaper than parchment and supported a large book trade, with stationers’ shops in the city.
The best-known institution is the House of Wisdom, a library and translation centre associated with Harun al-Rashid and al-Mamun. Scholars disagree about how formal or large it was. Much of the translation work was probably carried on by private patrons, families and scholars outside any single institution, and the idea of one grand academy may be an exaggeration. What is clear is that the court and the wider urban elite valued learning and paid for it. The result was a body of work in medicine, mathematics, astronomy, philosophy and geography that influenced scholarship in both the Islamic world and Europe.
Legacy
The Abbasid rise shaped the Islamic world for centuries. It shifted the empire’s political and cultural centre to Iraq, brought Persian administrative and literary traditions into the mainstream of Islamic civilisation, and made Baghdad a model city. Even after the caliphs lost real power, the title kept its prestige, and the intellectual heritage of the early Abbasid period continued to inspire scholars far beyond Iraq.