In 1193, the Nalanda University was sacked by Bakhtiyar Khalji, a Turk;[22] this event is seen by scholars as a late milestone in the decline of Buddhism in India. Khilji is said to have asked if there was a copy of the Koran at Nalanda before he sacked it. The Persian historian Minhaj-i-Siraj, in his chronicle the Tabaquat-I-Nasiri, reported that thousands of monks were burned alive and thousands beheaded as Khilji tried his best to uproot Buddhism and plant Islam by the sword;[23] the burning of the library contin­ued for several months and "smoke from the burning manuscripts hung for days like a dark pall over the low hills."[24]

Source: Wikipedia.org