Archeological excavations in Mohenjadaro, Harappa in the Sindh plains found inscriptions relating to medicinal uses of Neem, deer horn, pearl, etc were found. These products are extensively used in Siddha system of medicine. This goes on to say about the rich tradition of Siddha system.
This system was popularized eons ago by the famed 18 Siddhars (18 Saintly people who by their meditation and ascetic practices attained mystical powers). These Siddhars or Siddhas are found to have lived between 1000 BC and 500 AD. They had their own teams and traveled from villages to villages curing people for free from their physical ailments.
The 18 Siddhars are
All these Siddhars or Siddhas were Saivaite Tamils who have authored wonderful books on various aspects of Siddha system of medicine.