he oldest references to the concept of guru are found in the earliest Vedic texts of Hinduism.
The guru, and gurukul – a school run by guru, were an established tradition in India by the 1st millennium BCE, and these helped compose and transmit the various Vedas, the Upanishads, texts of various schools of Hindu philosophy, and post-Vedic Shastras ranging from spiritual knowledge to various arts.
By about mid 1st millennium CE, archaeological and epigraphical evidence suggest numerous larger institutions of gurus existed in India, some near Hindu temples, where guru-shishya tradition helped preserve, create and transmit various fields of knowledge.
These gurus led broad ranges of studies including Hindu scriptures, Buddhist texts, grammar, philosophy, martial arts, music and painting.