On February 13, 1258, the Mongol army led by Hulagu Khan sacked Baghdad. They massacred the population and burned the House of Wisdom. They threw so many books into the River Tigris that the water turned black with ink.

The steady conquest of Muslim Spain by Catholic forces eroded the western center of Islamic learning. Cordoba fell in 1236, Seville in 1248, and finally Granada in 1492. In 1499, Cardinal Cisneros burned over 1 million Arabic books in Granada's public square.

While Gutenberg invented the press in 1440, the Ottoman Empire banned the printing of Arabic books until 1727. They feared the desecration of religious texts. This caused a massive literacy gap: Europe printed millions of books, while Muslims relied on slow handwritten manuscripts.

For centuries, Islamic lands grew rich by taxing the Silk Road trade between China and Europe. In 1498, Vasco da Gama discovered the sea route to India around Africa. This allowed Europe to trade directly with Asia, bypassing Muslim lands.

Initially, Islam encouraged Ijtihad (independent reasoning). Over time, a more conservative approach prevailed, favoring Taqlid (imitation) and tradition. Some historians argue that Al-Ghazali's attack on philosophy (though nuanced) encouraged a shift away from empirical science.

The unified Abbasid Caliphate fractured into smaller warring states (Sultanates). Instead of funding scientists, resources were diverted to constant internal wars between Mamluks, Seljuks, Ottomans, and Safavids.