Vajrayāna Buddhism, also known as Tantric Buddhism and Esoteric Buddhism, is often viewed as the third major school of Buddhism, alongside the Theravada and Mahayana schools. This classification is useful when talking about schools by geographic areas. Others classify Vajrayana as a subset of Mahayana Buddhism, a useful scheme when studying the practices of the schools. Vajrayana Buddhists themselves often classify their school as the final stage in the evolution of Indian Buddhist theory which they enumerate as: Hinayana, Mahayana, Vajrayana (see dharma wheel). None of these classification schemes are particularly inconsistent with the others when the context is understood.
Vajrayana exists today in the form of two major sub-schools:
The key advantage Vajrayana Buddhism claims to provide is an accelerated path to enlightenment. This is achieved through use of tantra, which are practical aids to spiritual development, and esoteric transmission (explained below). Whereas earlier schools might provide ways to achieve nirvana over the course of many lifetimes, Vajrayana techniques make this possible in a much shorter timeframe, perhaps in a single lifetime. Vajrayana Buddhists do not claim that Theravada or Mahayana practices are in any way invalid, only that they represent slower paths to the same goal.
use of various yoga techniques, including breath control (yantra) and the use of special hand positions (mudras)
use of an extensive vocabulary of visual aids, such as cosmic mandala diagrams which teach and map pathways to spiritual enlightenment
the use of ritual objects such as the vajra and bell, hand drum (damaru), sacred bells (ghanta), and spirit daggers (phurpa), and relics
use of specialized rituals rooted in Vajrayana cosmology and beliefs
As a side note, the sensational techniques of tantric sex are confined
the more extreme 'Left-Hand path' of Tantra, which uses taboo-breaking as a means of spiritual enlightenment. All mainstream branches of Vajrayana, including Shingon, belong to the more conservative Right-Hand path and do not practice these rites. Sexual symbolism, however, is common in Vajrayana iconography, where it often represents the marrying of wisdom and compassion.
It is from the tantra that Vajrayana Buddhism gets the alternative names of Mantrayana and Tantrayana. The word "Vajrayana" itself comes from vajra, a Sanskrit word which can mean "diamond" or "thunderbolt" and which also has the connotation of "reality". This gives rise to two more names for Vajrayana Buddhism: Diamond Vehicle, and Adamantine Vehicle (adamantine means "diamond-like"). The vajra (or dorje in Tibetan) is an important ritual object symbolizes wisdom, while the bell symbolizes compassion.
The other conspicuous aspect of Vajrayana Buddhism is that it is esoteric. In this context esoteric means that the transmission of certain accelerating factors only occurs directly from teacher to student and cannot be learned from a book. Many techniques are also commonly said to be secret, but some Vajrayana teachers have responded that the secrecy itself is not important but only a side-effect of the reality that the techniques have no validity outside the teacher-student lineage. The esoteric aspects of Vajrayana Buddhism results in several more names for the school: Secret Buddhism, Esoteric Mahayana, and Esoteric Buddhism (the most common name in Japan).
The esoteric transmission framework can take varying forms. The Nyingma school of Tibetan Buddhism uses a method called dzogchen. Other Tibetan Buddhist schools and the Shingon school in Japan use an alternative method called mahamudra.
The Japanese Vajrayana teacher Kukai expressed a view contrary to this by making a clear distinction between Mahayana and Vajrayana. Kukai characterises the Mahayana in its entirety as exoteric, and therefore provisional. From this point of view the esoteric Vajrayana is the only Buddhist teaching which is not a compromise with the limited nature of the audience to which it is directed, since the teachings are said to be the Dharmakaya (the principle of enlightenment) in the form of Mahavairocana, engaging in a monologue with himself. From this view the Hinayana and Mahayana are provisional and compromised aspects of the Vajrayana - rather than seeing the Vajrayana as priamrily a form of Mahayana Buddhism.
Some aspects of Vajrayana have also filtered back into Mahayana. In particular, the Vajrayana fondness for the fearsome and macabre may be found in weakened form in Mahayana temples where protector deities may be found glaring down at visitors.
Regardless, early texts were appearing around the early 4th century.
Nalanda University in northern India became a center for the development of Vajrayana theory, although it is likely that the university followed, rather than led, the early Tantric movement. India would continue as the source of leading-edge Vajrayana practices up through the 11th century.
Vajrayana Buddhism had mostly died out in India by the 13th century, its practices merging with Tantric Hinduism, and both tantric religions experiencing pressure from the rising importance of Islam.
In the second half of the 20th century a sizeable number of Tibetan exiles fled the Communist Chinese to establish Tibetan Buddhist communities in northern India, particularly around Dharamsala. They remain the primary practitioners of Tantric Buddhism in India.
In 804, the Emperor Kammu of Japan sent the intrepid monk Kukai to the Tang capital at Chang'an to retrieve the latest Buddhist knowledge. Kukai absorbed the Vajrayana thinking and synthesized a version which he took back with him to Japan, where he founded the important Shingon school of Buddhism, a school which continues to this day.
In the 13th century, long after the original wave of Vajrayana Buddhism had died out in China itself, two Tibetan eminent Sakyapa teachers, Sakya Pandita Kunga Gyaltsen and Chogyal Phagpa, visited the Mongolian royal court. Marco Polo was serving the royal court at about the same time. In a competition between Christians, Moslems, and Buddhists held before the royal court, Prince Godan found Tibetan Buddhism to be the most satisfactory and adopted it as his personal religion, although not requiring it of his subjects. As Kublai Khan had just conquered China (establishing the Yuan Dynasty), his adoption of Vajrayana led to the renewal of Tantric practices in China as the ruling class found it useful to emulate their leader.
Vajrayana would decline in China and Mongolia with the fall of the Yuan Dynasty, replaced by resurgent Daoism, Confucianism, and Pure Land Buddhism. However, Mongolia would see yet another revival of Vajrayana in the 17th century, with the establishment of ties between the Dalai Lama in Tibet and the remnants of the Mongol Empire. This revived the historic pattern of the spiritual leaders of Tibet acting as priests to the rulers of the Mongol empire. Tibetan Buddhism is still practiced as a folk religion in Mongolia today despite more than 80 years of state-sponsored communism.