Bhakti yoga is a devotional form of yoga, usually associated with Theistic Hinduism. It is therefore focused on faith, love for and worship of a personal God, such as Shiva, Shakti or Krishna. It is taught in key works like the Bhagavad Gita as one of the forms of yoga, and became a major current of Hindu yoga in the second half of the 1st millenium CE, when it was promoted and celebrated by south Indian poet saints like the Alvars and Nayanars. Forms of Bhakti yoga include the singing of hymns, stories and songs (Kirtan), dancing, prayer, bowing, and performing puja rituals.
According to Geoffrey Samuel, our "best evidence to date" suggests that yogic practices "developed in the same ascetic circles as the early śramaṇa movements (Buddhists, Jainas and Ajivikas), probably in around the sixth and fifth centuries BCE." This occurred during what is called the ‘Second Urbanisation’ period. According to Mallinson and Singleton, these traditions were the first to use psychophysical techniques, mainly known as dhyana and tapas. but later described as yoga, to strive for the goal of liberation (moksha, nirvana) from samsara (the round of rebirth).
^ Andrew J. Nicholson (2013). Unifying Hinduism: Philosophy and Identity in Indian Intellectual History. Columbia University Press. p. 26. ISBN 978-0-231-14987-7., Quote: "From a historical perspective, the Brahmasutras are best understood as a group of sutras composed by multiple authors over the course of hundreds of years, most likely composed in its current form between 400 and 450 BCE."
The Bhagavad Gita ('Song of the Lord') is part of the Mahabharata and also contains extensive teachings on Yoga. According to According to Mallinson and Singleton, the Gita "seeks to appropriate yoga from the renunciate milieu in which it originated, teaching that it is compatible with worldly activity carried out according to one's caste and life stage; it is only the fruits of one's actions that are to be renounced." In addition to an entire chapter (ch. 6) dedicated to traditional yoga practice, including meditation, it introduces three prominent types of yoga:
During the Gupta period (4th to 5th centuries), a movement of northern Mahāyāna Buddhism termed Yogācāra began to be systematized with the writings of the Buddhist scholars Asanga and Vasubandhu. Yogācāra Buddhism received the name as it provided a "yoga," a systematic framework for engaging in the practices that lead through the path of the bodhisattva towards awakening and full Buddhahood. Its teachings can be found in the comprehensive and encyclopedic work, the Yogācārabhūmi-Śāstra (Treatise on the Foundation for Yoga Practitioners), which was also translated into Tibetan and Chinese and thus exerted a profound influence on the East Asian Buddhist and Tibetan Buddhist traditions. According to Mallinson and Singleton, the study of Yogācāra Buddhism is essential for the understanding of yoga's early history, and its teachings influenced the text of the Pātañjalayogaśāstra.