In general, the official history of the four tantras is that they were taught by the medicine Buddha, passed on by Jivakakumara, through Nagarjuna, Vagbhata, and his grandson, Candra-ananda, who taught to them to Vairocana in the eighth century. Vairocana translated them into Tibetan, and they were concealed by King Trisrong Detsen in a pillar at Samye. Three hundred years later, they were revealed by the eleventh century treasure finder Trapa Ngonshe, and finally wound up in the hands of the twelfth century physician, Yuthog Yonten Gonpo, the author of the earliest commentaries on the Four Tantras.
However, when we examine the history of the Four Tantras, we find that it's authorship was shrouded in controversy from the very beginning.
The first historical works we have related to the Four Tantras are two texts found in the famed collection of early medical texts, called the cha lag bco brgyad i.e. The Eighteen Sections: the first is a text called the khog dbub khyung chen lding ba i..e The Historical Outline, Soaring Great Eagle, ascribed to Yuthog the younger. This text is of somewhat doubtful authenticity according to some scholars, but regardless of its provenance, seems to have set the tone for the later khog dbubs literature. The second text is a anonymous visionary account of the teaching of tantra and its entrustment to Atreya and Jivakakumara called the brgyud pa'i rnam thar med thabs med pa i.e. The Indispensable Liberation Account of the Lineage.
These two texts are critical for understanding how the group of 12th century doctors who edited the Four Tantras and their students viewed the formation of their lineage and are critical to latter khog dbubs literature by the sixteen century doctor and historian Zurkhar Lodo Gyalpo (Zur mkhar blo gros rgyal po) and Desri Sangye Gyatso (sde srid sang rgya rgya mtsho), the famed regent of the Fifth Dalai Lama.
The Great Eagle is the source for one of clearest articulations of the uniqueness of the Tibetan Medical traditions. It lists eleven points detailing the superiority of the Four Tantra tradition over other medical traditions:
1) The superiority of being the pinnacle of all vehicles of healing science because all the Buddhaword and treatises of medical science is clearly shown in this text.
2) The superiority of being the king of tantras since it overwhelms the all other tantras of medical therapy
3) The superiority of being a general commentary upon all therapies of medical science since it clearly comments on all medical treatments without confusion.
4) The superiority of being the foundation of all medical science since all illnesses, symptoms and methods of treatment are completely covered.
5) The superiority of being the source of all medical science since all the divisions of systems of medical treatment spread from this.
6) The superiority of being the mirror of medical science because all illness are clearly seen without obstruction.
7) The superiority of being concise summary of all topics medical science because of gathering the essentials of medical treatment.
8) The superiority of being a stream of nectar because of remove the torment of illness.
9) The superiority of being the bestower of fearlessness and safety, protecting from the demon of death.
10) The superiority of being the crown jewel of all migrating beings since the hopes of all patients are fulfilled impartially.
11) The superiority of staying healthy, preventing illness, balancing the humors of the patient, lengthening life, and fame and longevity in this life.
After the introduction, The Great Eagle contains an account of the liberation of Dharmakaya Samantabhadra, and the formation of samsara. This arrangement sets the tone for later examples of medical khog dbubs literature, with Zurkhar following suit, albeit with a more sutra-based cosmogony.
The Indispensable Liberation Account of the Lineage is probably the earliest clear location where we have the assertion that the Four Tantras were a terma revealed by Trapa Nonshe.
Within the Great Origins of Treasures, (gter 'byung chen mo), the earliest systematic account of the terma traditon, the famed terton, Guru Chowang (chos kyi dbang phyug, 1212-1270) wrote in 1264:
The tantras of medicine were concealed in the mind, and revealed as Buddha word: eighteen major tantras were taught, rTsa ra ka's Tantra of Eight Divisions; The Tantra of the Crystal Mirror; The Tantra of the Drop of Nectar; and so on, The Great Seer Dungi Thorsug and Khe'u Kunjod Yiley Kye and so on gathered the teachings together and spread the teachings. Afterwards, in order to make them safe, concealed them as treasures in boxes of rhinoceros hide in India at the Sandal Groves of Vajrasana, the Sapphire Stupa of Oddiyana, the Asura Cave, and all the forests of Nepal, in the Go'u Deshan Cave of China, and so on.
Later on, Padma of Oddiyana and Nagarjunagarbha, and Muteg Thubgyal, and so on revealed these treasures and acted on behalf of sentient beings. In the end, having spread them in the country of Tibet, there were many discoveries of tantras concealed in many treasure caches.
In the later translation period, within the treasure cycles of dhakini medicine treatments, the omniscient revealed many treasures in the countries of Indian, China, the border lands, and the demon lands, and so on, many scriptures of Buddhaword, the tantra of the eigth limbs and so on; and many scriptures of treatises, the eight limb treatises and so on, and various intimate instructions, the eight limbs of intimate instructions and so on. [The Autobiography and Instructions of Gu-ru Chos-kyi-dbang-phyug, Voll II, page. 85]
A clear picture emerges that by latter half of the 13th century, Nyingma scholars were firmly asserting that systems of Tibetan Medicine depended on the gter ma tradition and that the ultimate origin of Tibetan Medicine was bka', vacana, or Buddhaword. The Great Eagle origin accounts are heavily grounded in Dzogchen cosmology, and that Four Tantras, whatever their ultimate origin, where being propagated in the 12th and 13th century by doctors with strong Nyingma connections. There are a number of features of the root tantra, undoubtedly the latest layer in the composition of the Four Tantras, which show clear influence of earlier Dzogchen tantras.
Now then, how were such claims received? Without going into the whole question of treasures and their authenticity, the ideas espoused in The Great Eagle and the Great History of Treasures were immediately rejected by another group of doctors, who were following the Indian tradition of the Ashtangahridayasamhita. These 13th century conservatives are well represented by Chomdan Rigpey Raltri (bcom ldan rig pa'i ral gri, 1227-1305), a famous Kadampa master. In his Flower Ornament of Medical Science (gso ba rig pa rgyan gyi me tog) he states quite unambiguously:
Some others claim that within the texts of medical practice, there are non-Buddhist and Buddhist i.e. non-Buddhist tantras and both Buddhist sutras and tantras. Within tantras, there is a root tantra, an explanatory tantra, an intimate instruction tantra, and a continuation tantra and so on. All of them are treatises written by Tibetans. Sutras and tantras are the discourses of the Tathagatas, medical science [texts] are treatises composed by persons.
One interesting facet that has not received much attention is the conflation of the term tantra as used in medicine and the term as used in Buddhist literature. Perhaps the earliest use of the term tantra is applied to the original text of which the Caraka Samhita is a commentary i.e. the Agniveshatantra. In Chowang's citation we see a clear reference to this text, "...rTsa ra ka's Tantra of Eight Divisions". Because of this incidental usage of the term tantra, the doctors who were involved in composing the Four Tantras, or so it seems, sought the opportunity to elevate their system of medicine over the competing, Indian system of Ayurveda which was then current and wide spread in Central Tibet.
Among Tibetans, the debate over the origins of the Four Tantras has continued right up to the present day, and there is voluminous literature on both sides of issues. I do not think that any serious text critical scholar can deny the fact however that the Tibetan scholars who argued for indigenous composition were completely correct in their assessments of the text as it stood in front of them.
Much more research is needed before we can say for certain by whom or when the Four Tantras were composed, but it is definite that they took their final form in the late 12th century, and that the adherents of this text began to make claims for its special status as bka' or vacana, Buddhaword nearly from the beginning.