Religion and Religious Communities under the Abbasids

The Abbasids came to power in 750 and made Iraq the centre of their caliphate, founding Baghdad in 762. From the eighth through tenth centuries, caliphal courts and scholars shaped religious debates across a realm that extended through Syria, Egypt, Iran and other provinces. As provincial dynasties gained power, religious institutions and communities continued to work within new political arrangements. The Mongol conquest of Baghdad in 1258 ended the Abbasid caliphate there.

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Islamic law and scholarly authority

Muslim scholars interpreted the Quran and the Sunna, the Prophet Muhammad’s remembered practice, to answer questions of worship, family, property and public conduct. This body of interpretation, called fiqh or Islamic jurisprudence, developed through teaching, debate and the transmission of legal reports. A madhhab, or school of law, was a scholarly tradition that shaped legal interpretation. Sunni and Shi‘i traditions differed first over who should lead the Muslim community after Muhammad’s death. Sunni Muslims accepted the succession of caliphs beginning with Abu Bakr, while Shi‘i Muslims held that Muhammad had designated Ali, his cousin and son-in-law, and that rightful leadership continued through Ali’s descendants, the Imams.

Abu Hanifa, Malik ibn Anas, al-Shafi‘i and Ahmad ibn Hanbal became the namesakes of the four major Sunni schools. Their teachings and the work of later students shaped distinct methods for weighing scripture, reports and reasoning. These schools took shape over generations; by the tenth century, they had become important affiliations for many Sunni Muslims. Shi‘i Muslims developed their own legal scholarship, with authority tied to the Imams, religious leaders in the family of Ali.

The mihna and the limits of caliphal doctrine

In 833, Caliph al-Ma’mun began the mihna, a state examination of religious scholars and officials over whether the Quran was created in time or was God’s eternal, uncreated word. He sent orders to Baghdad requiring judges and prominent scholars to affirm the createdness doctrine before holding office. Those who disagreed could lose their posts or testimony rights.

Ahmad ibn Hanbal, a leading Baghdad scholar, refused to affirm the doctrine and was imprisoned after interrogation. Al-Mu‘tasim and al-Wathiq continued the policy with varying intensity. Caliph al-Mutawakkil ended the tests in 849, and the dismissal of the chief judge and release of those detained marked their final close in 851–52. The controversy made the question of who could define belief practical: the caliph could command judges, while scholars built authority through teaching and adherence to religious reports.

Shi‘i leadership and Abbasid politics

The Abbasid claim to rule did not resolve competing ideas of rightful leadership. In 817, al-Ma’mun appointed Ali al-Rida, a descendant of Ali whom Shi‘i Muslims recognized as an Imam, as heir to the caliphate. The appointment drew opposition from Abbasid supporters in Baghdad. The caliph changed official ceremonial color from black to green to signal the new alignment, but Ali al-Rida died in 818 before succeeding him.

A later shift came in 945, when the Buyids, Shi‘i military rulers from northern Iran, entered Baghdad and took effective political power while preserving the Abbasid caliph. Buyid rulers sought caliphal titles and recognition, even as their own commanders controlled the army and government. The episode shows how the caliph’s religious and ceremonial standing could continue when another dynasty directed state power.

Christian, Jewish and Zoroastrian communities

Christian churches and communities maintained their own leaders and learning. In ninth-century Baghdad, Syriac-speaking scholars translated Greek works into Arabic, and the Christian physician Hunayn ibn Ishaq became a prominent translator of medical texts. Physicians compared and annotated inherited works, adding observations drawn from their practice.

Jewish communities in Iraq and Iran had recognized communal leadership and centres of religious study. The exilarch, or head of the eastern Jewish communities, stood alongside the sages of academies at Sura and Pumbeditha in southern Iraq; Baghdad became another scholarly centre after the tenth century. In Persian provinces, Zoroastrian communities continued to copy sacred books and compose religious arguments during the ninth and tenth centuries.

Muslim rulers treated Jews, Christians and Zoroastrians as dhimmis, protected communities with subordinate legal standing and tax obligations. Regulations could also distinguish them in public dress. In the ninth century, al-Mutawakkil ordered Christians, Jews and Zoroastrians to wear distinctive yellow headcloths and belts. The order made legal rank visible through clothing.

Endowments and religious provision

A waqf was an endowment: a property or asset assigned to produce income for a specified religious or charitable purpose. Managers collected rents or other revenue and used it for teaching, student meals, patient care, traveller lodging or worship. This system connected a founder’s intention to routine work such as collecting income, buying food, paying staff and maintaining buildings.

Baghdad’s Mustansiriyya, founded by Caliph al-Mustansir and opened in 1234, brought instruction in four Sunni legal traditions into one college. Shops, houses and agricultural properties supplied income for its staff and resident students. The same endowed-income model supported hospitals and traveller lodges, where administrators used assigned property revenue to pay staff and provide food or accommodation.