I felt sick to my stomach to learn about destruction of Nalanda, Takshila, Vikramshila, Sharada peeth, Vallabhi and other universities & libraries. These weren't places of religious worship. Ancient and medieval knowledge, over 20 million manuscripts burnt to ashes just like that.
A lot of knowledge gone indeed. Takshashila was conquered by the Hunas, Sveta-Hunas and Alchon Hunas and there was the Turk Shahi and Hindu Shahi dynasties (both were Hindu and Buddhist rules, the Hunas embraced Hinduism). This coincided with the decline of the Kushan Empire and the Gupta Empire. Four centuries later, Ghazni would invade the region.
As for Alauddin Khilji, who destroyed Nalanda and Vikramshila.. he was assassinated by Malik Kafur. This story is interesting; Malik Kafur was born a Hindu boy Manik, he was abducted during the 1299 invasion of Gujarat by Khilji's general, Nusrat Khan. He was a beautiful boy so he was auctioned off for 1000 dinars, enslaved and converted to Islam. His new name Kafur served to remind him his place. Kafur did rise up in the ranks and become a general who helped lead incursions to Kakatyas, Hoysalas and Pandyas empires. The Bollywood film Padmavati showed that the eunuch general Kafur had a homoerotic relationship with Khilji (although, it only remained a queer bait in the film), and Kafur's actor, Jim Sarbh, stated how the only way to humanise Khilji was through Malik Kafur's eyes. I would have loved to see Malik Kafur get humanised though - after all, he was the one who got ripped from his home, sold off and converted to Islam, turned into eunuch, called a kafur all his life.. Because in the end, Malik Kafur ended up poisoning Khilji, killing his children and taking Khilji's youngest wife. Maybe it was Kafur's final act of revenge after getting sold, converted and sexually abused. Bollywood will never explore this though.