Which historical text provides the earliest description of Bakhtiar Khilji's invasion of Bihar?

Q. Which historical text provides the earliest description of Bakhtiar Khilji's invasion of Bihar?
Answer: Tabaqat-e-Nasiri
Notes: Tabaqat-e-Nasiri, authored by Minhaj-i-Siraj in Persian, offers the first account of Bakhtiar Khilji's Bihar invasion. It details the destruction of Nalanda and other universities, and is a key source on early Delhi Sultanate history.