The theistic character evolved almost simultaneously with the non-theistic religions. The important deities of these religions were not primarily Vedic ones, but those that came from unorthodox sources. The primary factor that motivated these creeds was Bhakti, the single-soul devotion of the worshipers to a personal God with some moral link. This led to the evolution of different religious sects like Vaishnavism. Shaivism and Saktism, which came to be regarded as components of orthodox Brahmanism. These sects in course of time, came o have a significant impact on the popular forms of Buddhism and Jainism.
The worship of Yakshas and Nagas and other folk deities constituted the most important part of primitive religious beliefs, in which Bhakti had a very important role to play. There is ample evidence about the prevalence of this form of worship among the people.
The history of the above movements from the end of the Gupta period till the first decade of the AD 13th century is century is concerned mainly with South India. Vaishnava poet saints known as Alvars preached single-minded devotion for Vishnu and their songs were collectively known as Prabandhas.
1. A Sutra in Panini’s Ashtadhyayi refers to the worshippers of Vasudeva (Krishna).
2. The Chhandogya Upanishad also speaks of Krishna, the son of Devaki, a pupil of the sage Ghora Angirasa, who was a sun-worshiping priest.
3. A large number of people worshiped Vashudeva Krishna exclusively as their personal God and they were at first known as the Bhagavatas.
4. The Vasudeva-Bhagavata cult grew steadily, absorbing within its fold other Vedic and Brahminic divinities like Vishnu (primarily, an aspects of the Sun) and Narayana (a cosmic God)
5. From the late Gupta period, the name mostly used to designate this Bhakti cult was Vaishnava , indicating the predominance of the Vedic Vishnu element in it with emphasis on the doctrine of incarnations.
Panini refers to a group of Shiva worshipers as Shiva Bhagavatas. They were characterised by the iron lances and clubs that they carried along with their skin garments.
The Shiva movement in the south flourished at the beginning through the activities of many of the 63 saints known in Tamil as Nayanars (Shiva-bhakts).
Their appealing emotional songs in Tamil were called Tevaram Stotras and also as Dravida Veda and ceremonially sung in the local Shiva Temples. It must be noted that the Nayanars hailed from all the castes. This was supplemented on the doctrinal side by a large number of Shiva intellectuals, whose names were associated with several forms of Shiva movements like Agaamanta, Shudha and Vira-shaivism.