Yoga has first been mentioned in the oldest Indian sacred text of Rig Veda.
Yoga is one of the shaddarshanas (6 schools) of Indian philosophy, and its use as an intervention to healing dates back to hundreds of years ago.
Yoga therapy finds its roots in the philosophy of the 5 layers of the body as per the Taittriya Upanishad. In his explanation of psychosomatic diseases, Sage Vashishtha explains to Lord Rama the concept of why disturbances in the level of mind, may percolate into the physical body and manifest as a disease.