Niyama (The five "observances"): Śauca (purity, clearness of mind, speech and body), Santosha (contentment, acceptance of others and of one's circumstances), Tapas (persistent meditation, perseverance, austerity), Svādhyāya (study of self, self-reflection, study of Vedas), and Ishvara-Pranidhana (contemplation of God/Supreme Being/True Self).
^ James Mallinson, "Sāktism and Hathayoga," 28 June 2012.
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According to Crangle, some researchers have favoured a linear theory, which attempts "to interpret the origin and early development of Indian contemplative practices as a sequential growth from an Aryan genesis",[note 4] just like traditional Hinduism regards the Vedas to be the ultimate source of all spiritual knowledge.[note 5] Thomas McEvilley favors a composite model where pre-Aryan yoga prototype existed in the pre-Vedic period and its refinement began in the Vedic period.
Vajrayana is also known as Tantric Buddhism and Tantrayāna. Its texts were compiled starting with 7th century and Tibetan translations were completed in 8th century CE. These tantra yoga texts were the main source of Buddhist knowledge that was imported into Tibet. They were later translated into Chinese and other Asian languages, helping spread ideas of Tantric Buddhism. The Buddhist text Hevajra Tantra and Caryāgiti introduced hierarchies of chakras. Yoga is a significant practice in Tantric Buddhism.
Ascetic practices (tapas), concentration and bodily postures used by Vedic priests to conduct yajna (sacrifice), might have been precursors to yoga.[note 9] Vratya, a group of ascetics mentioned in the Atharvaveda, emphasized on bodily postures which may have evolved into yogic asanas. Early Samhitas also contain references to other group ascetics such as munis, the keśin, and vratyas. Techniques for controlling breath and vital energies are mentioned in the Brahmanas (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 10]