"The Muhammadan historian, indifferent to distinctions among idolators, states that the majority of the inhabitants were "clean shaven Brahmans," who were all put to the sword. He evidently means Buddhist monks, as he was informed that the whole city and fortress were considered to be a college, which the name Bihar signifies. A great library was scattered. When the victors desired to know what the books might be no man capable of explaining their contents had been left alive. No doubt everything was burnt. The multitude of images used in Medieval Buddhist worship always inflamed the fanaticism of Muslim warriors to such fury that no quarter was given to the idolators. The ashes of the Buddhist sanctuaries at Sarnath near Benares still bear witness to the rage of the image breakers. Many noble monuments of the ancient civilization of India were irre trievably wrecked in the course of the early Muhammadan invasions. Those invasions were fatal to the existence of Buddhism as an organized religion in northern India, where its strength resided chiefly in Bihar and certain adjoining territories. The monks who escaped massacre fled, and were scattered over Nepal, Tibet, and the south. After A.D. 1200 the traces of Buddhism in upper India are faint and obscure.231"
January 1, 1970
https://en.wikiquote.org/wiki/Decline_of_Buddhism_in_the_Indian_subcontinent