What really happened when the Mongols took Baghdad?

In February 1258, an army led by Hulegu, a Mongol prince, took Baghdad, the capital of the Abbasid Caliphate, after a series of provocations by the caliph. The Mongols had expected the caliph, al-Musta'sim, to send reinforcements for their army; his failure to do so, together with his arrogance in negotiations, convinced Hulegu to overthrow him. Baghdad was then left with about 30,000 troops. Mongol siege engines breached its fortifications within a couple of days, and the caliph surrendered on 10 February. Looting began three days later.

The sack, according to one reading, was not simply wanton destruction. Scholars, merchants who traded with the Mongols, and Christians were told to mark their doors so their houses would be spared, while the rest of the city was pillaged and killed for a full week. Nobody knows how many died: later Muslim writers said 800,000 to two million, and Hulegu himself claimed two million, a number described as obviously inflated. The caliph was wrapped in a carpet and trampled to death by horses, because shedding royal blood was a Mongol taboo.

Baghdad had been the epicentre of the Islamic Golden Age, with centres of learning such as the House of Wisdom, so the fall of the city is often told as the end of an era. That story needs care. Muslim writers traditionally blamed the decline of the Golden Age on this one event, but modern historians criticise that argument as simplistic. A 16th-century historian said so many books were thrown into the Tigris that the river ran black; Michal Biran has shown that large libraries reopened within two years. And Baghdad prospered under Hulegu's Ilkhanate, until later sieges by Timur and the Ottomans left it marginalized.