Mongol Invasion of Baghdad (1258)

Hulagu Khan's Mongol forces sacked the city of Baghdad in February 1258, executing the last Abbasid Caliph and massacring an estimated 200,000 to 800,000 inhabitants. The House of Wisdom — the world's greatest library and intellectual centre — was destroyed, its books thrown into the Tigris until the river reportedly ran black with ink. The sack ended the Islamic Golden Age that had preserved and expanded Greek knowledge through Europe's Dark Ages. The geopolitical vacuum left behind reshaped trade routes, weakened Islamic political unity, and contributed to the Ottoman Empire's eventual rise.