In short, when Muhammad Bakhtiyar became aware of the nature of the country, and saw that his men were tired and exhausted, and that many had been sl… - Muhammad bin Bakhtiyar Khalji

Khalji’s military exploits in the east also resulted in conversions to Islam. About the end of the twelfth or the beginning of the thirteenth century, he marched into Bihar and attacked the University centres of Nalanda, Vikramshila and Uddandapur, erecting a fortress at the site of Uddandapur or Odantapuri. The Buddhist monks in these places were massacred and the common people, deprived of their priests and teachers, turned some to Brahmanism and some to Islam. Buddhism did not die out immediately or completely in Bihar. But Bakhtiyar’s raid on Bihar did deliver a shattering blow to Buddhism and its lost followers were gained mainly by Islam.

After receiving a robe from the Sultan he returned to Behar. Great fear of him prevailed in the minds of the infidels of the territories of Lakhnauti, Behar, Bang (Bengal), and Kamrup... It is related by credible authorities that mention of the brave deeds and conquests of Malik Muhammad Bakhtiyar was made before Rai Lakhmaniya, whose capital was the city of Nudiya…
Next year Muhammad Bakhtiyar prepared an army, and marched from Behar. He suddenly appeared before the city of Nudiya with only eighteen horsemen, the remainder of his army was left to follow. Muhammd Bakhtiyar did not molest any man, but went on peaceably and without ostentation, so that no one could suspect who he was. The people rather thought that he was a merchant, who had brought horses for sale. In this manner he reached the gate of Rai Lakhmaniya’s palace, when he drew his sword and commenced the attack. At this time the Rai was at his dinner, and golden and silver dishes filled with food were placed before him according to the usual custom. All of a sudden a cry was raised at the gate of his palace and in the city. Before he had ascertained what had occurred, Muhammad Bakhtiyar had rushed into the palace and put a number of men to the sword. The Rai fled barefooted by the rear of the palace, and his whole treasure, and all his wives, maid servants, attendants, and women fell into the hands of the invader. Numerous elephants were taken, and such booty was obtained by the Muhammadans as is beyond all compute. When his army arrived, the whole city was brought under subjection, and he fixed his headquarters there.
Rai Lakhmaniya went towards Sanknat and Bengal, where he died. His sons are to this day rulers in the territory of Bengal. When Muhammad Bakhtiyar had taken possession of the Rai’s territory, he destroyed the city of Nudiya and established the seat of his government at Lakhnauti. He brought the surrounding places into his possession, and caused his name to be read in the Khutba and struck on the coins. Mosques, colleges, and monasteries were raised everywhere by the generous efforts of him and his officers, and he sent a great portion of the spoil to Sultan Kutbu-d din.

Khilji’s starring role in the destruction of Indian Buddhism is well-documented in contemporaneous Muslim sources and cannot be shifted to unnamed Hindu bogeys so cavalierly.