Buddhism has evolved into myriad schools that can be roughly grouped into three families. The Sanskrit term used for these forms is yana or vehicles. Each yana sees itself as representing the true, original teachings of the Buddha, although some schools believe that the dialectic nature of Buddhism allows its format, terminology, and techniques to adapt over time in response to changing circumstances.
The three vehicles
The three vehicles include, first, the Hinayana or "Lesser vehicle". The Hinayana vehicle represents the class of practitioners who seek enlightenment for themselves, and is represented in literature by those teachings that encourage arhatship rather than Buddhahood.
All traditions accept the Hinayana teachings as being authentic (and they are generally considered to be the earliest). However, "Hinayana schools", sometimes referred to as Nikaya schools, are those schools who recognise solely the Hinayana teachings as authentic. The Theravada school, or "Way of the Elders", is the only surviving Nikaya tradition. Theravada is practiced today in Sri Lanka, Burma, Laos, Thailand, and portions of Vietnam and Malaysia.
The second vehicle is the Mahayana, or "Great Vehicle", which emphasizes universal compassion and the selfless ideal of the bodhisattva. In addition to the Hinayana scriptures, Mahayana schools recognize all or part of a genre of scriptures that were first put in writing around 1 CE. These later scriptures are concerned with the purpose of achieving Buddhahood through following the ten stages of the Bodhisattva'a progress to Buddhahood across three countless aeons of lifetimes; because of the immense time, many Mahayana schools accept the idea of working towards rebirth in a Pure Land, where the attainment of enlightenment is much easier. Mahayana is practiced today in China, Japan, Korea, parts of India, and portions of Vietnam.
The third vehicle is the Vajrayana or "Diamond Vehicle" (also known as Tantric Buddhism), which, while sharing many of the basic concepts of Mahayana, also includes a vast array of spiritual techniques designed to enhance Buddhist practice.
One component of the Vajrayana is harnessing psycho-physical energy as a means of developing profoundly powerful states of concentration and awareness. These profound states are in turn used as an efficient path to Buddhahood. Using these techniques, it is claimed that a practitioner can achieve Buddhahood in as little as three years! In addition to the Hinayana and Mahayana scriptures, Vajrayana Buddhists recognise a large body of texts that include the Buddhist Tantras. Vajrayana is practiced today mainly in Tibet, Nepal, Bhutan, Mongolia, areas of India, Kalmykia and, to a limited extent, in China and Japan.
History of the schools
Three months after the passing of Gautama Buddha, The First Council was held by the Sangha. At this point, no conflict about what the Buddha taught is known to have occurred, so the teachings were divided into various parts and each was assigned to an elder and his pupils to commit to memory. These groups of people often cross-checked with each other to ensure that no omissions or additions were made.
At the Second Council, one hundred years later, it was not the dharma that was called into question but the monks' code of rules or vinaya. This resulted in the formation of the Sthaviravadin and Mahasanghika schools. Opinions differ on the cause of the split: the Sthaviravadins described their opponents as lax monks who had ceased to follow all the vinaya rules, while the Mahasanghikas argued that the Buddha had never intended a rigid adherence to all the minor rules. After this initial division, more were to follow. Schism in early Buddhism was typically not on points of doctrine (orthodoxy), but in the area of practice (orthopraxy). So if two schools shared a vinaya, but were in dispute over doctrinal matters, it was not unlikely that they would continue to practice together. However, if one group disputed the vinaya of another, this would often prevent common practice.
In the 3rd century BC the Third Council occurred, where small sects called into to question not only the vinaya but the details of the Dharma. The chairman of the Council, Moggaliputta Tissa, compiled a book called the Kathavatthu, which was meant to refute the heretical, false views and theories held by some sects. Moggaliputta's views were of course disputed by his opponents. The version of the scriptures that had been established at the Third Council, including the vinaya and the Abhidhamma commentaries, was taken to Sri Lanka by the son of Emperor Ashoka. There it was eventually committed to writing in the Pali language. The Pali Canon remains the only complete set of Nikaya scriptures to survive, although fragments of other versions exist.
Between the 1st century BC to the 1st century AD, the terms Mahayana and Hinayana were first used in writing, in, for example, the Lotus Sutra.
During and after the 2nd century AD, versions of the Mahayana vision became clearly defined in the works of Nagarjuna, Asanga, Shantideva, Ashvagosha, and Vasubandhu.
Around the 1st century AD, Buddhism spread from India through successive waves of merchants and pilgrims. It reached as far as Arabia to the west, and eastward to southeast Asia, where the first records of Buddhism date from around 400AD. Mahayana established a major regional center in what is today Afghanistan, and from there it spread to China, Korea, Mongolia, and Japan. In 475, the Indian monk Bodhidharma travelled to China and established the Chan (Chinese; Japanese: Zen), school. During the first millennium AD, monks from China such as Yijing and Xuanzang made pilgrimages to India.
At one time, different Turkic and Tocharian groups along the northern fringe of East Turkestan (modern Xinjiang in western China) adhered to the Theravada school. However, Buddhism there was supplanted by the introduction of Islam around 1000 AD.
Vajrayana also evolved at this stage carried from India to Tibet around 800 AD by teachers such as Padmasambhava and Atisha. There it initially coexisted with native belief systems such as Bön, but later came to largely supplant or absorb them. An early form of esoteric Vajrayana known as Shingon was also transmitted by the priest Kukai to Japan, where it continues to be practiced.
There is still an active debate as to whether or not Tantrism was initially developed within Buddhism or Hinduism. Buddhist literature tends to predate the later puranic Tantras, and there is some evidence to suggest that the basic structure of tantra depends upon the Mahayana Buddhist philosophical schools.
2 -[Buddhism : Buddha's life]
3 -[Buddhism : Principles of Buddhism]
4 -[Buddhism : The three vehicles]
5 -[Buddhism : Tripi?aka]