Yoga (Sanskrit, Pāli: योग, /ˈjəʊɡə/, yoga) is a commonly known generic term for physical, mental, and spiritual disciplines which originated in ancient India. Specifically, yoga is one of the six āstika (“orthodox”) schools of Hindu philosophy. It is based on the Yoga Sūtras of Patañjali. Various traditions of yoga are found in Hinduism, Buddhism, Jainism and Sikhism.
Pre–philosophical speculations and diverse ascetic practices of first millennium BCE were systematized into a formal philosophy in early centuries CE by the Yoga Sutras of Patanjali. By the turn of the first millennium, Hatha yoga emerged as a prominent tradition of yoga distinct from the Patanjali’s Yoga Sutras. While the Yoga Sutras focus on discipline of the mind, Hatha yoga concentrates on health and purity of the body.
Hindu monks, beginning with Swami Vivekananda, brought yoga to the West in the late 19th century. In the 1980s, yoga became popular as a physical system of health exercises across the Western world. Many studies have tried to determine the effectiveness of yoga as a complementary intervention for cancer, schizophrenia, asthma and heart patients. In a national survey, long-term yoga practitioners in the United States reported musculo–skeletal and mental health improvements.
Several seals discovered at Indus Valley Civilization sites, dating to the mid 3rd millennium BC, depict figures in positions resembling a common yoga or meditation pose, showing “a form of ritual discipline, suggesting a precursor of yoga,” according to archaeologist Gregory Possehl. Ramaprasad Chanda, who supervised Indus Valley Civilization excavations, states that, “Not only the seated deities on some of the Indus seals are in yoga posture and bear witness to the prevalence of yoga in the Indus Valley Civilization in that remote age, the standing deities on the seals also show Kayotsarga (a standing posture of meditation) position. It is a posture not of sitting but of standing.” Some type of connection between the Indus Valley seals and later yoga and meditation practices is speculated upon by many scholars, though there is no conclusive evidence.
Ascetic practices (tapas), concentration and bodily postures used by Vedic priests to conduct yajna (Vedic ritual of fire sacrifice) might have been precursors to yoga. Vratya, a group of ascetics mentioned in the Atharvaveda, emphasized on bodily postures which probably evolved into yogic asanas. Early Vedic Samhitas also contain references to other group ascetics such as, Munis, Kesins and Vratyas. Techniques for controlling breath and vital energies are mentioned in the Brahmanas (ritualistic texts of the Vedic corpus, c. 1000–800 BCE) and the Atharvaveda. Nasadiya Sukta of the Rig Veda suggests the presence of an early contemplative tradition.[note 4] Alexander Wynne, author of The Origin of Buddhist Meditation, observes that formless meditation and elemental meditation might have originated in the Upanishadic tradition. The earliest reference to meditation is in the Brihadaranyaka Upanishad, one of the oldest Upanishads. Chandogya Upanishad describes the five kinds of vital energies (prana). Concepts used later in many yoga traditions such as internal sound and veins (nadis) are also described in the Upanishad. Taittiriya Upanishad defines yoga as the mastery of body and senses.