Tribal people, "adivasis," living in and around forested areas of India have used medicinal herbs as their first line of defense against diseases for centuries and are considered the sources of many of the therapeutic properties of regional medicinal plants of India. Tribal healers are especially noted for their expertise in the use of "ottamoolis," powerful single plant remedies for healing specific illnesses. The empirical nature of traditional medicine is such that over centuries they have contributed significantly to region-specific medical knowledge of India. Their resources and knowledge are highly sought after by surrounding communities and by academics studying medicinal plants of the region. In many towns and villages across India, on market day, tribal people sell hard to find medicinal plants collected from the habitats they know well, and they consult for patients on the use and preparation of these medicines. While the tribal healer's knowledge is entirely experience based, many of their selections of medicinal plants and their corresponding illnesses overlap with the practices of Kerala Ayurvedic remedies, suggesting that over centuries indigenous folk knowledge had become part of the classical Ayurvedic pharmacology.
This highly sought-after healer of the Irula Tribe from Attapady, in the Western Ghat mountains of South India, was a specialist in healing skin diseases, febrile fevers, and with Manasika chikilsa, diseases of the mind. In addition to the medicinal herbs, he uses rituals, chants and song therapy which he considers sacred and specific for diseases of the mind. The vaidya saw much overlap in his practice as an herbalist, and as a practitioner of magical healing since he believes healing plants have magical properties. This belief shared by tribal societies across the world may refer to the psychoactive properties of plants.