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The Abbasid Caliphate

The Abbasid Caliphate (750-1258) moved Islam's capital to its new city of Baghdad and presided over the Islamic Golden Age — the House of Wisdom, algebra, hospitals, and the translation movement that preserved Greek science. Politically hollowed from the 10th century, it was extinguished when the Mongols destroyed Baghdad in 1258.

Key facts

Duration: 750-1258 (shadow line in Cairo to 1517)
Capital: Baghdad, founded 762 as the Round City
Golden-age caliphs: Harun al-Rashid and al-Ma'mun (8th-9th centuries)
Learning: House of Wisdom; translation movement; al-Khwarizmi's algebra
Baghdad at peak: Plausibly the world's largest city
Political decline: From the 10th century, caliphs under Buyid and Seljuk control
End: Mongol sack of Baghdad, February 1258

The revolution and the Round City

The Abbasids took the caliphate from the Umayyads in the revolution of 750 — claiming descent from the Prophet’s uncle Abbas, riding a coalition of the discontented, and sealing the change with the era’s customary massacre of the old dynasty. Their second caliph, al-Mansur, planted a new capital in 762 where the Tigris nears the Euphrates: Baghdad, laid out as a perfect Round City of concentric walls. Within a century it was plausibly the largest city on Earth — the metropolis of the Thousand and One Nights, whose fictional frame preserves the real glamour of caliph Harun al-Rashid’s court.

The Golden Age

The Abbasid centuries made Baghdad the planet’s intellectual capital. The translation movement — state-funded, sustained for generations, centred on institutions remembered as the House of Wisdom — carried Greek philosophy, medicine, and mathematics (with Persian and Indian science) into Arabic, saving much that would otherwise have vanished. On that foundation the age built its own: al-Khwarizmi’s al-jabr gave the world algebra and, via his name, the algorithm; Hindu-Arabic numerals spread west; hospitals, observatories, and paper mills (the craft arriving from the east) multiplied; al-Razi and later ibn Sina wrote the medicine Europe would study for six centuries. The empire this learning crowned stretched, at its height, from North Africa to Central Asia.

The long hollowing

From the 10th century the caliphs’ worldly power drained away — provinces went their own ways under their own dynasties (Spain had never submitted; Egypt raised the rival Fatimid caliphate), while in Baghdad itself Persian Buyid and then Turkish Seljuk warlords ruled through the caliph, who retained immense religious prestige and shrinking acreage. Saladin, in the 12th century, still coined and prayed in the Abbasid’s name while owing him nothing.

1258

The end came from the steppe. In February 1258 Hulagu’s Mongols took Baghdad, killed the last reigning caliph al-Musta’sim — rolled in a carpet and trampled, by the famous account, to avoid spilling royal blood — and gave the city a destruction from which its world primacy never returned; the libraries went into the Tigris with everything else. The Mamluks of Cairo installed a refugee Abbasid as shadow caliph — a legitimacy ornament maintained until the Ottomans took Egypt in 1517 — but the caliphate as a power had died with its city: the institution whose golden age named an entire civilisation’s, ended in an afternoon’s sack.

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