In the thirteenth century, the Mongol Empire under Genghis Khan and his successors launched a series of devastating invasions into the Muslim world, first destroying the Khwarazmian Empire in Central Asia and Persia during the 1220s. The most catastrophic single event came in 1258 CE, when Hulagu Khan's forces besieged and sacked Baghdad, the seat of the Abbasid Caliphate for over five hundred years. The city's libraries, including collections built up since the era of the House of Wisdom, were destroyed, irrigation systems were wrecked, and a large portion of the population was killed, including the last Abbasid caliph in Baghdad, al-Musta'sim. The fall of Baghdad is widely regarded by historians as marking the symbolic end of the classical Islamic Golden Age, though scholarship and culture continued to flourish in other centers such as Cairo. The Mongol advance into the Levant was finally halted by Mamluk forces from Egypt at the Battle of Ain Jalut in 1260 CE, a turning point that prevented further Mongol expansion into North Africa. In a striking historical turn, many of the Mongol khanates that ruled former Muslim territories, notably the Ilkhanate in Persia and the Golden Horde in the Russian steppe, gradually converted to Islam themselves within a few generations, becoming absorbed into the broader Muslim civilization they had once devastated.
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