Much has been written by scholars about the origin of Mantrayāna in Buddhism. It may not be totally incorrect to state that Vajrayāna differs from Mantrayāna only in terms of the severity or intensity of practice. While Yōgācāra promises the attainment of śūnayatā, Vajrayāna, along with śūnyatā, promises Mahāsukha or Great Bliss.
According to traditional sources of Vajrayāna, Buddha, in the sixteenth year after sambodhi, convened a council at Dhānyakaṭaka (or Dharaṇīkōṭa in Guntur, Andhra), turned the wheel of dharma for the third time and revealed the esoteric teachings of Mantrayāna. This place and śrīparvata are held to be the places where Vajrayāna originated.
Bhavabhūti describes śrīparvata as the center of Buddhist tantra in Mālatīmādhava and speaks of a Bauddha bhikṣuṇī named Kapālakuṇḍalā who practices tāntrika vidhis. Folklore is abundant with stories of Nāgārjuna attaining siddhi on śrīparvata. A fourteenth-century work named Nikāyasaṅgraha describes Vajrayāna as vajraparvatanivāsī nikāya. Some scholars point to the fact that Guhyasamāja tantra is also famous as śrīsamāja.
According to a few knowledgeable Vajrayāna practitioners I have had the pleasure to converse with, Līlāvajra, a famous teacher of Vajrayāna who was the chief disciple of Lakṣmīṅkarā (one of the eighty-four siddhas, sister of Indrabhūti and the author of Advayasiddhi) lived for a long time on śrīśaila and taught tantra to disciples. Based on tradition, many Vajrayāna practitioners such as Kalu Rinpoche are of the opinion that śrīparvata is the most suitable place for attaining the siddhi of Kurukullā.