History of Yoga - Literary sources

Ascetic practices (tapas) are referenced in the Brāhmaṇas (900 BCE and 500 BCE),[28] early commentaries on the vedas. In the Upanishads, an early reference to meditation is made in Brihadaranyaka Upanishad,[29] one of the earliest Upanishads (approx. 900 BCE). The main textual sources for the evolving concept of Yoga are the middle Upanishads, (ca. 400 BCE), the Mahabharata (5th c. BCE) including the Bhagavad Gita (ca. 200 BCE), and the Yoga Sutras of Patanjali (200 BCE-300 CE).