Toward the middle of the 8th century, a revolt broke out against the Umayyads when the recently converted Muslims in the provinces became dissatisfied with their limited opportunities in Islamic society. The Abbasids, who now seized power, were able to trace their lineage back to Muhammad’s uncle al-Abbas. This gave them far greater legitimacy as Islamic rulers than the Umayyads.

Under the Abbasids, the capital of the realm was moved from Syria to Iraq, first to Baghdad in 762 and then to Samarra in 836. The move eastward also meant growing influence from Iranian culture at the expense of the Mediterranean Byzantine culture. This period, considered a golden age, reached its culminations under the caliphs Harun al-Rashid (786-809) and al-Mamun (813-833). Literature, theology, philosophy, and the natural sciences flourished, and the House of Wisdom (Bayt al-hikma), where Hellenistic works from Antiquity were translated into Arabic, was founded in Baghdad. The caliphs had enormous palaces and palace-cities built that were decorated with legendary magnificence.

The caliphate was not expanded under the Abbasids, and in fact experienced increasing pressure from Byzantine forces in the eastern Mediterranean. In the 9th century, the empire also started to break up from within. A renegade Umayyad had founded an independent realm on the Iberian Peninsula, and in North Africa, the Abbasids’ hegemony was soon only a matter of form. There were similar developments in parts of Iran, where local governors founded independent dynasties that rarely if ever paid taxes to the Abbasids.

The Abbasids finally lost their political power when the Buyids occupied Baghdad in 945 and took over the Abbasids’ Iraqi and Iranian holdings. The Buyids were originally mercenaries that came from northern Iran. In contrast to the Abbasids, they were Shiites. They let the Abbasid caliphs stay on in Baghdad, but only as religious rulers over the Sunni Muslims. The Buyids stayed in power for nearly a century, until they were defeated by the Seljuk Turks in 1055.

A distinctive Islamic form of decoration was developed under the Abbasids: the Samarra style, featuring geometric and vegetal patterns. Like the Arabic script, the Samarra style was to play an important role in artistic decoration in many contexts, from stucco and stone in buildings to woodcarvings, glass, metal, and ceramics, which also underwent important technical improvements. The new guidelines in art and architecture that emerged from Baghdad and Samarra were copied throughout the Islamic world – from the Atlantic coast to Central Asia.