1st Buddhist council (5th century BC)

The first Buddhist council was held soon after the death of the Buddha under the patronage of king Ajatasatru, and presided by a monk named Mahakasyapa, at Rajagaha (today's Rajgir). Its objective was to record the Buddha's sayings (sutra) and codify monastic rules (vinaya).

2nd Buddhist council (383 BC)

The second Buddhist council was convened by king Kalasoka and held at Vaisali , following conflicts between the conservative and liberal elements of Sangah.

The conservative schools insisted on strict adherence to monastic rules (vinaya). The secessionist Mahasangikas argued for more relaxed monastic rules, which could appeal to a large majority of monastic and lay people (hence their name "majority" assembly).

The council ended with the rejection of the Mahasanghikas. They left the council and maintained themselves for several centuries in northwestern India and Central Asia according to Kharoshti inscriptions found near the Oxus and dated c. 1st century AD.

In time, up to 18 schools of the traditional Buddhist thought arose, the only remaining one today being the Eastern Theravada school. Other schools included the Sarvastivadin and the Dharmaguptaka in Northwestern India.

3rd Buddhist council (c. 250 BC)

The third Buddhist council was convened by the Mauryan king Ashoka (260-218 BC) at Pataliputra (today's Patna), and held by the monk Moggaliputta. Its objective what to reconcile the different schools of Buddhism, and to purify the Buddhist movement, particularly from opportunistic factions which had been attracted by the royal patronage.

The Pali canon (Tipitaka, or Tripitaka in Sanskrit, lit. the "Three Baskets"), which are the texts of reference of traditional Buddhism and considered to be directly transmitted from the Buddha, was formalized at that time. They consist of the doctrine (the Sutra Pitaka), the monastic discipline (Vinaya Pitaka) and an additional new body of subtle philosophy (the Abhidharma Pitaka).

Also, emissaries were sent to various countries in order to spread Buddhism, as far as the Greek kingdoms in the West (in particular the neighboring Greco-Bactrian Kingdom, and possibly even farther to the Mediterranean according to the inscriptions left on stone pillars by Ashoka).

After 250 BC, the Sarvastivadin (who had been rejected by the 3rd council, according to the Theravada tradition) and the Dharmaguptaka schools became quite influential in northwestern India and Central Asia, up to the time of the Kushan Empire in the first centuries of the common era. The Dharmaguptakas were characterized by a belief that Buddha was separate, and above, the rest of the Buddhist community. The Sarvastivadin believed that past, present and future are all simultaneous. They may have contributed some formative influence to Mahayana.

4th Buddhist council (c. 100 AD)

The fourth Buddhist council was convened by the Kushan emperor Kanishka, around 100 AD at Jalandhar or in Kashmir, and is usually associated with the formal rise of Mahayana Buddhism. Theravada Buddhism does not recognize the authenticity of this council, and it is sometimes called the "council of heretical monks".

It is said that Kanishka gathered 500 Bhikkhus in Kashmir, headed by Vasumitra, to edit the Tripitaka and make references and remarks. It is said that during the council, there were all together three hundred thousand verses and over nine million statements compiled, and that it took twelve years to complete.

This council did no rely on the original pali canon (the Tipitaka). Instead, a set of new scriptures were approved, as well as fundamental principles of Mahayana doctrine. The new scriptures, usually in the Gandhari vernacular and the Kharosthi script, were rewritten in the classical language of Sanskrit, to many scholars a turning point in the propagation of Buddhist thought.

The new form of Buddhism was characterized by an almost God-like treatment of the Buddha, by the idea that all beings have a Buddha-nature and should aspire to Buddhahood, and by a syncretism due to the various cultural influences within northwestern India and the Kushan Empire, especially from Zoroastrianism and Greco-Buddhism.

From that point on, and in the space of a few centuries, Mahayana was to flourish and spread into Central Asia, China, Korea and Japan (introduction of Buddhism in 538 AD).