Vaishnavism originates in the latest centuries BCE and the early centuries CE, as an amalgam of the heroic Krishna Vasudeva, the "divine child" Bala Krishna of the Gopala traditions, and syncretism of these non-Vedic traditions with the Mahabharata canon, thus affiliating itself with Vedism in order to become acceptable to the orthodox establishment. Krishnaism becomes associated with bhakti yoga in the medieval period.[note 1]
Although Vishnu was a Vedic solar deity, he is mentioned more often compared to Agni, Indra, and other Vedic deities, thereby suggesting that he had a major position in the Vedic religion. Other scholars state that there are other Vedic deities, such as water deity Nara (also mentioned as Narayana-Purusha in the Brahmanas layer of the Vedas), who together form the historical roots of Vaishnavism. In the late-Vedic texts (~1000 to 500 BCE), the concept of a metaphysical Brahman grows in prominence, and the Vaishnavism tradition considered Vishnu to be identical to Brahman, just like Shaivism and Shaktism consider Shiva and Devi to be Brahman respectively.
The ancient emergence of Vaishnavism is unclear, the evidence inconsistent and scanty. According to Dalal, the origins may be in Vedic deity Bhaga, who gave rise to Bhagavatism. According to Preciado-Solís, the Vedic deities Nara and Narayana form one of the Vedic roots of Vaishnavism. According to Dandekar, Vaishnavism may have emerged from merger of several ancient theistic traditions, where the various deities were integrated as different avatars of the same god. In Dandekar theory, Vaishnavism emerged at the end of the Vedic period, closely before the second urbanisation of northern India, in the 7th to 4th century BCE. Vasudeva and Krishna, "the deified tribal hero and religious leader of the Yadavas," gained prominence, merged into Bhagavan Vasudeva-Krishna, due to the close relation between the Vrsnis and the Yadavas.
This was followed by a merger with the cult of Gopala-Krishna of the cowherd community of the Abhıras at the 4th century CE. The character of Gopala Krishna is often considered to be non-Vedic. According to Dandekar, such mergers consolidated the position of Krishnaism between the heterodox sramana movement and the orthodox Vedic religion. The "Greater Krsnaism", states Dandekar, then merged with the Rigvedic Vishnu.
Syncretism of various traditions and Vedism resulted in Vaishnavism. At this stage that Vishnu of the Rig Veda was assimilated into non-Vedic Krishnaism and became the equivalent of the Supreme God. The appearance of Krishna as one of the Avatars of Vishnu dates to the period of the Sanskrit epics in the early centuries CE. The Bhagavad Gita was incorporated into the Mahabharata as a key text for Krishnaism.
Finally, the Narayana-cult was also included, which further brahmanized Vaishnavism. The Nara-Narayana cult may have originated in Badari, a northern ridge of the Hindu Kush, and absorbed into the Vedic orthodoxy as Purusa Narayana. Purusa Narayana may have later been turned into Arjuna and Krsna.
This complex history is reflected in the two main historical denominations of Vishnavism. The Bhagavats, worship Vasudeva-Krsna, and are followers of brahmanic Vaishnavism, while the Pacaratrins regard Narayana as their founder, and are followers of Tantric Vaishnavism.
According to Hardy,[note 2] there is evidence of early "southern Krishnaism," despite the tendency to allocate the Krishna-traditions to the Northern traditions. South Indian texts show close parallel with the Sanskrit traditions of Krishna and his gopi companions, so ubiquitous in later North Indian text and imagery. Early writings in Dravidian culture such as Manimekalai and the Cilappatikaram present Krishna, his brother, and favourite female companions in the similar terms. Hardy argues that the Sanskrit Bhagavata Purana is essentially a Sanskrit "translation" of the bhakti of the Tamil alvars.
Devotion to southern Indian Mal (Tirumal) may be an early form of Krishnaism, since Mal appears as a divine figure, largely like Krishna with some elements of Vishnu. The Alvars, whose name can be translated "sages" or "saints", were devotees of Mal. Their poems show a pronounced orientation to the Vaishnava, and often Krishna, side of Mal. But they do not make the distinction between Krishna and Vishnu on the basis of the concept of the Avatars. Yet, according to Hardy the term "Mayonism" should be used instead of "Krishnaism" when referring to Mal or Mayon.
Most of the Gupta kings, beginning with Chandragupta II (Vikramaditya) (375-413 CE) were known as Parama Bhagavatas or Bhagavata Vaishnavas.
Early medieval period
After the Gupta age, Krishnaism rose to a major current of Vaishnavism, and Vaishnavism developed into various sects and subsects, most of them emphasizing bhakti, which was strongly influenced by south Indian religiosity.
Vaishnavism in the 8th century came into contact with the Advaita doctrine of Adi Shankara. Many of the early Vaishnava scholars such as Nathamuni, Yamunacharya and Ramanuja, contested the Advaita Vedanta doctrines and proposed Vishnu bhakti ideas instead. Vaishnavism flourished in predominantly Shaivite South India during the seventh to tenth centuries CE with the twelve Alvars, saints who spread the sect to the common people with their devotional hymns. The temples that the Alvars visited or founded are now known as Divya Desams. Their poems in praise of Vishnu and Krishna in Tamil language are collectively known as Naalayira Divya Prabandha(4000 divine verses).
Later medieval period
The Bhakti movement of late medieval Hinduism started in the 7th-century, but rapidly expanded after the 12th-century. It was supported by the Puranic literature such as the Bhagavata Purana, poetic works, as well as many scholarly bhasyas and samhitas.
This period saw the growth of Vashnavism Sampradayas (denominations or communities) under the influence of scholars such as Ramanujacharya, Vedantha Desikacharya, Madhvacharya, Nimbarkacharya and Vallabhacharya. Bhakti poets or teachers such as Manavala Mamunigal, Namdev, Ramananda, Surdas, Tulsidas, Eknath, Tyagaraja, Chaitanya Mahaprabhu and many others influenced the expansion of Vaishnavism.Even Meera bai(princess of Mehwar and Rajasthan)took part in this specific movement. These Vaishnavism sampradaya founders challenged the then dominant Shankara's doctrines of Advaita Vedanta, particularly Ramanuja in the 12th century, Vedantha Desikacharya and Madhva in the 13th, building their theology on the devotional tradition of the Alvars (Shri Vaishnavas).
In North and Eastern India, Krishnaism gave rise to various late Medieval movements: Nimbarka and Ramananda in the 14th century, Sankaradeva in the 15th and Vallabha and Chaitanya in the 16th century. Historically, it was Chaitanya Mahaprabhu who founded congregational chanting of holy names of Krishna in the early 16th century after becoming a sannyasi.
During the 20th century, Vaishnavism has spread from India and is now practiced in many places around the globe, including North America, Europe, Africa, Russia and South America. This is largely due to the growth of the ISKCON movement, founded by A.C. Bhaktivedanta Swami Prabhupada in 1966.