Early Buddhist schools
The early Buddhist schools are those schools into which the Buddhist monastic saṅgha initially split, due originally to differences in vinaya and later also due to doctrinal differences and geographical separation of groups of monks.
The original saṅgha split into the first early schools (generally believed to be the Sthavira nikāya and the Mahāsāṃghika) a significant number of years after the passing away of Gautama Buddha. According to scholar Collett Cox "most scholars would agree that even though the roots of the earliest recognized groups predate Aśoka, their actual separation did not occur until after his death."
Later, these first early schools split into further divisions such as the Sarvāstivādins, the Dharmaguptakas, the Vibhajyavāda, and ended up numbering traditionally to about 18 or 20 schools. In fact, there are several overlapping lists of 18 schools preserved in the Buddhist tradition, totaling about twice as many, though some may be alternative names. It is thought likely that the number is merely conventional.
The textual material shared by the early schools is often termed the Early Buddhist Texts and these are an important source for understanding their doctrinal similarities and differences.
According to the scriptures (Cullavagga XI.1 ff), three months after the passing of Gautama Buddha, the first council was held at Rajagaha by some of his disciples who had attained arahantship. At this point, Theravāda tradition maintains that no conflict about what the Buddha taught occurred; the teachings were divided into various parts and each was assigned to an elder and his pupils to commit to memory.
The accounts of the council in the scriptures of the schools differ as to what was actually recited there. Purāṇa is recorded as having said: "Your reverences, well chanted by the elders are the Dhamma and Vinaya, but in that way that I heard it in the Lord's presence, that I received it in his presence, in that same way will I bear it in mind." [Vinaya-pitaka: Cullavagga XI:1:11].
The Second Buddhist council took place approximately one hundred years after Gautama Buddha's parinirvāṇa. Virtually all scholars agree that the second council was a historical event. Traditions regarding the Second Council are confusing and ambiguous, but it is agreed that the overall result was the first schism in the sangha, between the Sthavira nikāya and the Mahāsāṃghikas, although it is not agreed upon by all what the cause of this split was.
The textual sources agree that the first split was between the Sthaviravāda and the Mahāsāṃghika. However, after this initial division, more were to follow. Some modern scholars argue that the first split occurred in the intervening period between the second and third councils, and was probably about monastic discipline. However, only two ancient sources (the Dīpavaṃsa and Bhavya's third list) place the first schism before Aśoka, and none attribute the schism to a dispute on Vinaya practice.
Tradition largely holds that Buddhism split into 18 schools, but different sources give different lists of them, and scholars conclude that the number is merely conventional.
Theravādin sources state that, in the 3rd century BCE, a third council was convened under the patronage of Aśoka, but no mention of this council is found in other sources. Some scholars argue that there are certain implausible features of the Theravādin account which imply that the third council was ahistorical. The remainder consider it a purely Theravāda-Vibhajjavāda council. It is generally accepted, however, that one or several disputes did occur during Aśoka's reign, involving both doctrinal and disciplinary (vinaya) matters, although these may have been too informal to be called a "council". The Sthavira school had, by the time of Aśoka, divided into three sub-schools, doctrinally speaking, but these did not become separate monastic orders until later.
According to the Theravādin account, this council was convened primarily for the purpose of establishing an official orthodoxy. At the council, small groups raised questions about the specifics of the vinaya and the interpretation of doctrine. The chairman of the council, Moggaliputta Tissa, compiled a book, the Kathavatthu, which was meant to refute these arguments. The council sided with Moggaliputta and his version of Buddhism as orthodox; it was then adopted by Emperor Aśoka as his empire's official religion. In Pali, this school of thought was termed Vibhajjavāda, literally "thesis of [those who make] a distinction".
The distinction involved was as to the existence of phenomena (dhammas) in the past, future and present. The version of the scriptures that had been established at the third council, including the Vinaya, Sutta and the Abhidhamma Pitakas (collectively known as the "Tripiṭaka"), was taken to Sri Lanka by Emperor Aśoka's son, the Venerable Mahinda. There it was eventually committed to writing in the Pali language. The Pāli Canon remains the most complete set of surviving Nikāya scriptures, although the greater part of the Sarvāstivādin canon also survives in Chinese translation, some parts exist in Tibetan translations, and some fragments exist in Sanskrit manuscripts, while parts of various canons (sometimes unidentified), exist in Chinese and fragments in other Indian dialects.
Whatever might be the truth behind the Theravādin account, it was around the time of Aśoka that further divisions began to occur within the Buddhist movement and a number of additional schools emerged, including the Sarvāstivāda and the Saṃmitīya. All of these early schools of Nikāya Buddhism eventually came to be known collectively as "the eighteen schools" in later sources. Unfortunately, with the exception of the Theravāda, none of these early schools survived beyond the late medieval period by which time several were already long extinct, although a considerable amount of the canonical literature of some of these schools has survived, mainly in Chinese translation. Moreover, the origins of specifically Mahāyāna doctrines may be discerned in the teachings of some of these early schools, in particular in the Mahāsānghika and the Sarvāstivāda.
During and after the third council, elements of the Sthavira group called themselves Vibhajjavādins. One part of this group was transmitted to Sri Lanka and to certain areas of southern India, such as Vanavasi in the south-west and the Kañci region in the south-east. This group later ceased to refer to themselves specifically as "Vibhajjavādins", but reverted to calling themselves "Theriyas", after the earlier Theras (Sthaviras). Still later, at some point prior to the Dipavamsa (4th century), the Pali name Theravāda was adopted and has remained in use ever since for this group.
The Pudgalavādins were also known as Vatsiputrīyas after their putative founder. Later this group became known as the Sammitīya school after one of its subdivisions. It died out around the 9th or 10th century CE. Nevertheless, during most of the early medieval period, the Sammitīya school was numerically the largest Buddhist group in India, with more followers than all the other schools combined. The Sarvāstivādin school was most prominent in the north-west of India and provided some of the doctrines that would later be adopted by the Mahāyāna. Another group linked to Sarvāstivāda was the Sautrāntika school, which only recognized the authority of the sutras and rejected the abhidharma transmitted and taught by the Vaibhāṣika wing of Sarvāstivāda. Based on textual considerations, it has been suggested that the Sautrāntikas were actually adherents of Mūlasarvāstivāda. The relation between Sarvāstivāda and the Mūlasarvāstivāda, however, is unclear.
Between the 1st century BCE and the 1st century CE, the terms "Mahāyāna" and "Hīnayāna" were first used in writing, in, for example, the Lotus Sutra.
Although the various early schools of Buddhism are sometimes loosely classified as "Hīnayāna" in modern times, this is not necessarily accurate. According to Jan Nattier, Mahāyāna never referred to a separate sect of Buddhism (Skt. nikāya), but rather to the set of ideals and doctrines for bodhisattvas. Paul Williams has also noted that the Mahāyāna never had nor ever attempted to have a separate vinaya or ordination lineage from the early Buddhist schools, and therefore each bhikṣu or bhikṣuṇī adhering to the Mahāyāna formally belonged to an early school.
Membership in these nikāyas, or monastic sects, continues today with the Dharmaguptaka nikāya in East Asia, and the Mūlasarvāstivāda nikāya in Tibetan Buddhism. Therefore, Mahāyāna was never a separate rival sect of the early schools. Paul Harrison clarifies that while Mahāyāna monastics belonged to a nikāya, not all members of a nikāya were Mahāyānists. From Chinese monks visiting India, we now know that both Mahāyāna and non-Mahāyāna monks in India often lived in the same monasteries side by side. Additionally, Isabella Onians notes that Mahāyāna works rarely used the term Hīnayāna, typically using the term Śrāvakayāna instead.
The Chinese Buddhist monk and pilgrim Yijing wrote about relationship between the various "vehicles" and the early Buddhist schools in India. He wrote, "There exist in the West numerous subdivisions of the schools which have different origins, but there are only four principal schools of continuous tradition." These schools are namely the Mahāsāṃghika nikāya, Sthavira, Mūlasarvāstivāda and Saṃmitīya nikāyas. Explaining their doctrinal affiliations, he then writes, "Which of the four schools should be grouped with the Mahāyāna or with the Hīnayāna is not determined." That is to say, there was no simple correspondence between a Buddhist monastic sect, and whether its members learn "Hīnayāna" or "Mahāyāna" teachings.
During the first millennium, monks from China such as Faxian, Xuanzang, and Yijing made pilgrimages to India and wrote accounts of their travels when they returned home. These Chinese travel records constitute extremely valuable sources of information concerning the state of Buddhism in India during the early medieval period.
By the time the Chinese pilgrims Xuanzang and Yijing visited India, there were five early Buddhist schools that they mentioned far more frequently than others. They commented that the Sarvāstivāda/Mūlasarvāstivāda, Mahāsāṃghika, and Saṃmitīya were the principal early Buddhist schools still extant in India, along with the Sthavira sect. The Dharmaguptakas continued to be found in Gandhāra and Central Asia, along the Silk Road.
It is commonly said that there were eighteen schools of Buddhism in this period. What this actually means is more subtle. First, although the word "school" is used, there was not yet an institutional split in the saṅgha. The Chinese traveler Xuanzang observed even when the Mahāyāna were beginning to emerge from this era that monks of different schools would live side by side in dormitories and attend the same lectures. Only the books that they read were different. Secondly, no historical sources can agree what the names of these "eighteen schools" were. The origin of this saying is therefore unclear.
In addition, the Dipavamsa lists the following six schools without identifying the schools from which they arose:
Sthaviravāda (上座部) was split into 11 sects. These were: Sarvāstivādin (説一切有部), Haimavata (雪山部), Vatsīputrīya (犢子部), Dharmottara (法上部), Bhadrayānīya (賢冑部), Sammitīya (正量部), Channagirika (密林山部), Mahisasaka (化地部), Dharmaguptaka (法蔵部), Kāśyapīya (飲光部), Sautrāntika (経量部).
Mahāsāṃghika (大衆部) was split into 9 sects. There were: Ekavyahārika (一説部), Lokottaravādin (説出世部), Gokulika (鶏胤部), Bahuśrutīya (多聞部), Prajñaptivāda (説仮部), Caitika (制多山部), Aparaśaila (西山住部), and Uttaraśaila (北山住部).
Noted Canadian Buddhist scholar A.K. Warder (University of Toronto) identifies the following eighteen early Buddhist schools (in approximate chronological order): Sthaviravada, Mahasamghika, Vatsiputriya, Ekavyavaharika, Gokulika (a.k.a. Kukkutika, etc.), Sarvastivada, Lokottaravada, Dharmottariya, Bhadrayaniya, Sammitiya, Sannagarika, Bahusrutiya, Prajnaptivada, Mahisasaka, Haimavata (a.k.a. Kasyapiya), Dharmaguptaka, Caitika, and the Apara and Uttara (Purva) Saila. Warder says that these were the early Buddhist schools as of circa 50 BCE, about the same time that the Pali Canon was first committed to writing and the presumptive origin date of the Theravada sect, though the term 'Theravada' was not used before the fourth century CE (see Ajahn Sucitto, (2012); see also A.K. Warder, Indian Buddhism, 3rd rev. ed. (Delhi: Motilal Banarsidass, 2000), chapters 8 and 9).
The Theravāda School of Sri Lanka, Burma, and Thailand is descended from the Sthaviravādin and (more specifically) the Vibhajjavāda School. It underwent two more changes of name. In the Indian accounts it is sometimes called the "Tāmraparnīya" (translation: Sri Lankan lineage), but there is no indication that this referred to any change in doctrine or scripture, while it is very obvious that it refers to geographical location. At some point prior to the Dipavamsa (4th century) the name was changed to "Theravāda", probably to reemphasize the relationship to the original "Sthaviravāda", which is the Sanskrit version of the Pāli term "Theravāda".
The Theravāda school is the only remaining school which is exclusively aligned with the philosophic outlook of the early schools. However, significant variation is found between the various Theravādin communities, usually concerning the strictness of practice of vinaya and the attitude one has towards abhidhamma. Both of these, however, are aspects of the Vibhajjavādin recension of the Tipiṭaka, and the variation between current Theravāda groups is mainly a reflection of accent or emphasis, not content of the Tipiṭaka or the commentaries. The Tipiṭaka of the Theravāda and the main body of its commentaries are believed to come from (or be heavily influenced by) the Sthaviravādins and especially the subsequent Vibhajjavādins.
The legacies of other early schools are preserved in various Mahāyāna traditions. All of the schools of Tibetan Buddhism use a Mūlasarvāstivāda vinaya and study the Sarvāstivādin abhidharma, supplemented with Mahāyāna and Vajrayāna texts. Chinese schools use the vinaya from the Dharmagupta school, and have versions of those of other schools also. Fragments of the canon of texts from these schools also survive such as the Mahāvastu of the Mahāsānghika School.
Discussion on the difference in their views includes Kathāvatthu and the Chinese or Tibetan translation of Samayabhedoparacanacakra (異部宗輪論), Abhidharmamahāvibhāsā-śāstra (大毘婆沙論), Abhidharmakośa-śāstra (俱舍論) Abhidharma-nyāyānusāra (順正理論), Abhidharma-kośa-samaya-pradīpikā (顯宗論) etc.