642 AD Burning of the Great Library of Alexandria. Several historians told varying accounts of a Muslim army led by sacking the city in 642 after the Byzantine army was defeated at the , and that the commander asked the what to do with the library. He gave the famous answer: "They will either contradict the Koran, in which case they are heresy, or they will agree with it, so they are superfluous." The Arabs subsequently burned the books to heat bathwater for the soldiers. It was also said that the Library's collection was still substantial enough at this late date to provide six months' worth of fuel for the baths.
651AD According to an account in , the Arab Commander wrote to Caliph about what should be done with the books of the Royal Library at the Persian capital of in the province of Khvârvarân (today known as Iraq). Umar wrote back: "If the books contradict the Qur'an, they are blasphemous. On the other hand, if they are in agreement, they are not needed." All the books were thrown into the Euphrates.