Nalanda's decline began before its final destruction, as Buddhism's institutional position in India weakened relative to a resurgent Hinduism and, from the twelfth century, the arrival of Turkic Muslim military campaigns into the Gangetic plain, but the university remained an active center of study into the final decades of the twelfth century.
In 1193 the Turkic military commander Bakhtiyar Khilji, leading a campaign into Bihar, attacked and destroyed the monastery, and later Persian chronicles, along with the account of the Tibetan historian Taranatha writing some centuries afterward, describe the library being burned and many resident monks killed, though the precise scale and circumstances of the destruction remain debated among modern historians working from limited and sometimes contradictory sources.
The destruction of Nalanda is conventionally treated as one of the defining episodes in the broader decline of institutional Buddhism in India, alongside the destruction of other major monastic universities such as Vikramashila in the same period, after which Buddhism survived in the subcontinent mainly in peripheral regions rather than as a major organized institutional presence.
The site was rediscovered and excavated by British colonial era archaeologists beginning in the nineteenth century, and the extensive ruins now form an Archaeological Survey of India protected site inscribed as a UNESCO World Heritage Site in 2016, while a newly established Nalanda University, founded nearby in 2010 as an international initiative, invokes the ancient institution's name and legacy without claiming direct institutional continuity with it.