From Alexander the Great to various Khan's, then Mughals, then Portuguese etc. Some important Indian texts were burned/destoryed in these attacks, For eg., the Nalanda University
Still, a lot of texts remained both in written format and in Oral format.
I feel like the role of Nalanda in Indian history has been greatly exaggerated.
The education system was very decentralized, and that's really why most things have survived.
There is not much evidence of concrete knowledge/resources being lost at Nalanda.
[1] https://web.archive.org/web/20220120055253/https://www.patna... [2] https://www.myindiamyglory.com/2017/09/11/nalanda-9-million-...
Also, think about it in this way: if some of the manuscripts there was the only copy available, were those really impactful?