These days it is common to find people claiming Tibetan Medicine originated with Tonpa Shenrab (ston pa gshen rab) and his son, Chebu Trishe (dbyad bu khri shes).
We have no texts about Shenrab that can be dated earlier than the tenth century, when the Bonpos began to reconstruct their own history prior to the Imperial period. Our main sources for information about Tonpa Shenrab come from three texts, the gZi brjid, the gZer mig, and a third text, the mDo 'dus.
Our source of information about the relation between Tibetan Medicine and Tonpa Shenrab comes from the latest of these three texts, the gZi brjid, which was composed in the 14th century.
According to the standard modern text book on the history of medicine[gso rig lo rgyus Beijing, 2004] used presently in Tibet, the ancient scholar Shenton Yeshe Lodo (gshen ston ye shes blo gro) asserts that Shenrab was born in 1957 BCE i.e. 3,975 years ago. Some modern historians assert he was born 1917 BCE (this is Chogyal Namkhai Norbu's conclusion), i.e. in a male rat year, 3,925 years ago. It is based on these approximate dates, that one often hears the assertion that Tibetan Medicine is tradition that dates back 4,000 years.
The book also includes the interesting statement by the famed Zurkhar Lodo Gyalpo (zur mkhar blo gros rgyal po) in his shes bya khog dbubs or Encyclopedic Outline:
At the same time that Bhagavan Shakyamuni arrived in the world, the one called Shenrab Miwoche arrived in Purang (in Western Tibet).Now, with this statement, there is a bit of an issue, if we accept Zurkhar's statement, we have to date the Buddha to date Shenrab. Our textbook continues by mentioning several dates for the birth of the Buddha: Atisha's date, 2,215 BCE; Sapan's dates, 2,213 BCE; the dates of the Phug Lug (phugs lugs) system of astrology, 961 BCE. The most recent, according to our textbook, would be the 2500 anniversary of the birth of the Buddha set by the Japanese as 1938 i.e. 562 BCE.
To these dates we should add the traditional Theravadin dates, 624 BCE, which is supported by the "traditional long chronology" based on the Dipavamsa, and so on, which holds that Buddha passed away 218 years prior to the coronation of Ashoka. Finally, on top of this are two more dates, that of "corrected long chronology" i.e. the traditional Pali account corrected by relying on Greek Historical records, which push this date up to the Japanese date given above. Finally, there is the so called "short chronology"(gaining currency because it is supported by much archaeology, Jain accounts of birth of Mahavira and so on forth) which put the passing of the Buddha a mere 100 years prior to the coronation of Ashoka, and this range of date now seems to be something the range of 484 BCE, but even here there are many options which can be seen on this paper on the issue: Notes on the Dates of the Buddha Shakyamuni.
It is difficult say when exactly Zurkhar thought the Buddha lived, as I have not been able to find a reference to a date in his works. So until further research, this is left undone. The main point is that he clearly thought the Buddha's dates set the dates for Shenrab.
So what does the gZi brjid say about Tonpa Shenrab and Medicine? It is as difficult to take the gZi rbjid seriously as a work on the purported life of Tonpa Shenrab as it is to take the Morte D'Arthur as serious history of King Arthur. The text contains the term Vaidurya i.e. in beturya 'od gyi rgyal po, Vaiduryaprabharaja, the eight Medicine Buddha siblings and so on that certainly cannot have entered Tibet any earlier that the eighth century. As it is represented to be an oral history of Tonpa Shenrab's career, and as it is a huge text, there is much work needed on this text before we can have an absolutely clear picture of it. One thing is certain though, it is a post-Buddhist text and uses all the conventional Buddhist terms for Buddhas imported from India.
The section on medicine in the chapter of phyva gshen is just a very brief summary of the most basic principles of sman dbyad, or medical therapy. One feature of this text is an unusual presentation of the humors: hot, cold, phlegm, bile and combination. The text goes on to say:
All heat is tamed by cool. All cold is tamed by warmth. All phlegm is divided by separation, all bile is extracted by collecting.
If there is a disturbance of the components ('du ba i.e. humors), it is tamed with balance. The affliction of ignorance is pulled out from the root by applying the twenty one thousand medical preparations to the twenty one thousand components.
There are four types of healing: healing of medicinal nectar; the healing of medicines that cure the body; the healing of skillful behavior, and neutral healing.
There are four treatments: pacifying with medicine, bloodletting, moxabustion, and the skillful mantras.
Apply whatever is necessary to the illness. Medicine's taste, effect, and post-digestive taste; those are warmth of taste, the intensity of effect, and the smoothness of post-digestive taste.
For illness, there is emetics, laxatives, and traces. Draw out with emetics, cleanse with laxatives, and pacify the traces for happiness.
There is no mention of Shenrab's son Chebu Trishe in this text. He first seems to appear in the Bon version of the Four Tantras, the gSo rig 'bum bzhi i.e. The Four Volumes of Healing Science. Virtually word for word identical with the Four Tantras apart from the introduction, it seems that this is the text that introduces Chebu Trishe. Further research is required to see if he appears in other Bon texts and from what era.
In general, Chebu Trishe is considered something like the Bonpo Jivakakumara, and Bonpos, as well as some Tibetan historians, would like the trace the history of Tibetan medicine from this personage.
Yeshe Lodo, mentioned above, composed a text on wounds, The Instructional Water that Revives the Dying, Healing Wounds asserting that Chebu Trishe condensed many medical instructions and so on about repairing cuts. The famed herbalist Tenzin Phuntsog (de'u dmar sge bshes bstan 'dzin phun tshogs) later repeats the same assertion in the Crystal Rosary ('khrungs dpe shel phreng). Also in his Deep and Clear Heart Essence (zab gsal snying thig), a text on the method of preparing bezoars he cites a text attributed to Chebu Trishe called The Whirling Swastika, Treating Poison (dug bcos gyung drung 'khyil). Other Tibetan physicians who have mentioned Chebu Trishe are Gong men Konchog Deleg (gong sman dkon mchog bde legs).
Whatever the truth of the matter, because of a rich cache of Bonpo medical literature, which for the most part has not been examined by western scholars, including this one, Tibetan physicians after the 14th century, the approximate date of the appearance of altered Bon version of the Four Tantras, paid respect to the Bon tradition of medicine because of the existence of texts atttributed to this perhaps mythological personage. But like everything with Tibetan history and medicine, indeed Buddhist history in general, there is lots more work to be done.