Nasir al-Din al-Tusi
With all other libraries in Baghdad, the House of Wisdom was destroyed by the army of Hulagu during the Siege of Baghdad. The books from Baghdad’s libraries were thrown into the Tigris River in such quantities that the river ran black with the ink from the books. Nasir al-Din al-Tusi rescued about 400,000 manuscripts which he took to Maragheh before the siege.