Professors or Teachers (Upādhyāya or Āchārya), roughly 160 in number including paṇḍits Resident monks (bhikṣu), roughly 1,000 in number According to Tāranātha, at Vikramashila's peak during the reign of King Chanaka (955–83), the dvārapāla were as follows: Ratnākaraśānti (Eastern Gate), Vāgīsvarakīrti (Western Gate), Ratnavajra (First Central Gate), Jñanasrimitra (Second Central Gate), Naropa (Northern Gate), and Prajñākaramati (Southern Gate). If this is correct, it must have been toward the end of Chanaka's reign given the generally accepted dates for Naropa (956–1041). Tantric preceptors Vikramaśīla was a centre for Vajrayana and employed Tantric preceptors. The first was Buddhajñānapāda, followed by Dīpaṁkarabhadra and Jayabhadra. The first two were active during Dharmapāla's reign, the third in the early to mid portion of the 9th century. Jayabhadra, a monk from Sri Lanka, was the first prominent commentator on the Cakrasamvara tantra. Śrīdhara was the next preceptor, followed by Bhavabhaṭṭa. The latter, also a prominent commentator on Cakrasamvara, may have been the mahāsiddha Bhadrapāda. He in turn was succeeded by three more prominent Cakrasamvara commentators, Bhavyakīrti, Durjayachandra, and Tathāgatarakṣita. Durjayachandra collaborated with the renowned Tibetan translator Rinchen Zangpo and his commentary became particularly important for the Sakya school, and Tathāgatarakṣita collaborated with Rin-chen grags. In chronological order: Buddhajñānapāda Dīpaṁkarabhadra Jayabhadra Śrīdhara Bhavabhaṭṭa Bhavyakīrti Līlavājra Durjaychandra Samayavajra Tathāgatarakṣita Bodhibhadra Kamalarakṣita Library The vast majority of the manuscripts contained within Vikramashila’s library have been lost following multiple historical upheavals including the Muslim raids of East India led by Bakhtiyar Khalji. Many of manuscripts fell prey to natural decay as the climate of the Indo-Gangetic plains is not favourable to the preservation of palm-leaf manuscripts. However, some of the manuscripts of Vikramashila’s library, have been discovered in Nepal and Tibet as many of the Buddhist monks fled to these regions following the collapse of the monastery. So far, five manuscripts have been identified that contain references to Vikramashila. One of these manuscripts is currently held at the British Library references the ‘Glorious Great Monastery of the King Vikramaśīla’ (śrīmadvikramaśīladevamahāvihāra) as the place of production and contains the text of the Aṣṭasāhasrikā Prajñāpāramitā. Layout and excavation The remains of the ancient university have been partially excavated in kahalgaon Bhagalpur district, Bihar state, India, and the process is still underway. Meticulous excavation at the site was conducted initially by B. P. Sinha of Patna University (1960–69) and subsequently by Archaeological Survey of India (1972–82). It has revealed a huge square monastery