The Bhakti movement originated in ancient Tamil Nadu and began to spread to the north during the late medieval ages when north India was under Islamic rule. The Islamic rulers were pressing public to convert religion from Hindu to Islam. The Bhakti movement had its own importance to save Hinduism. There was no grouping of the mystics into Shaiva and Vaishnava devotees as in the south. The movement was spontaneous and the mystics had their own versions of devotional expression.
In Hinduism Bhakti is religious devotion in the form of active involvement of a devotee in worship of the divine. Within monotheistic Hinduism, it is the love felt by the worshipper towards the personal God, a concept expressed in Hindu theology as Ista-devata.
The Bhakti Movement was a rapid growth of bhakti beginning in Tamil Nadu in Southern India with the Saiva Nayanars (4th-10th century CE) and the Vaisnava Alvars (3rd-9th century CE) who spread bhakti poetry and devotion throughout India by the 12th-18th century CE. The Alvars ("those immersed in God") were Vaishnava poet-saints who wandered from temple to temple singing the praises of Vishnu. They established temple sites (Srirangam is one) and converted many people to Vaishnavism. Their poems were collected in the 10th century as the Four Thousand Divine Compositions also referred to as Dravida Veda or Alwar Arulicheyalgal or Divya Prabhandham, which became an influential scripture for the Vaishnavas. The Alwars and Nayanmars were instrumental in propagating the Bakti tradition and played probably the most important role of reviving Hinduism from the dying embers. For the first time, Bagwan or God reached the masses and the masses were able to associate themselves with the religion. Another significant thing was that the Alwars and Naynmars came from various background and castes including that of the Sudras (working class). The Bhagavata Purana's references to the South Indian Alvar saints, along with its emphasis on a more emotional bhakti, have led many scholars to give it South Indian origins, though there is no definitive evidence of this.
The Bhagavad Gita introduces bhakti yoga in combination with karma yoga and jnana yoga, while the Bhagavata Purana expands on bhakti yoga, offering nine specific activities for the bhakti yogi. Bhakti in the Bhagavad Gita offered an alternative to two dominant practices of religion at the time: the isolation of the sannyasin and the practice of religious ritual. Bhakti Yoga is described by Swami Vivekananda as "the path of systematized devotion for the attainment of union with the Absolute". In the twelfth chapter of the Gita Krishna describes bhakti yoga as a path to the highest spiritual attainments.
The Bhakti movement had far-reaching effects on the people. Firstly, it helped a lot in removing the existing bitterness between the Hindus and the Muslims. Both became more tolerant towards each other.
Secondly, the Bhaktas exposed the hollowness of empty rituals and ceremonies and taught the people to give up evils like belief in superstitions etc. This movement delta a blow to the superiority of the Brahmins, for it propagated the equality of all men. This also helped in checking conversions.
Thirdly, the Bhakti reformers preached in the common language of the people, which gave rise to the vernacular languages such as Bengali in the east, Gujarati and Marathi in the west and Punjabi in the north.
It is a noteworthy feature of the movement in Karnataka that it began as much a socio-political movement as it was a religious phenomenon. Basavanna, Allamaprabhu, Akkamahadevi and Siddarama the leaders of this movement had a retinue of followers who belonged to many castes that were then considered lowly. Shivasharanas, the Veerashiava saints of the twelfth century were not insider critics of Hinduism. They spurned the Vedic hegemony in its entirety and preached Veerashivism which took little notice of the caste system. It did not hesitate to take the untouchables in to its fold. The movement had a literary component of lasting value in Vachana Sahitya. The movement was self critical what with its major proponents like Allamaprabhu and Basavanna being stark opponents of false Bhakti. Vachanas played a prominent role in the spread of this movement because they were composed in powerful Kannada.
Ramanujacharya the founder of Sri Vaishnava Philosophy stayed in Karnataka for a brief stint and he is well known for trying to throw open the doors of his religion and Vedic knowledge to Dalits.
Mathas (The Centres of institutionalized religion and castes) have played a dual role in the context of these movements. On the one hand they have received strong rebuttals by the leading lights of the movement for being too rigid. On the other hand, the Mathas have appropriated the movement and its literature and treating them as their own.
Another aspect of Bhakti movement in Karnataka as elsewhere is the large scale participation the devotees belonging to the backward and oppressed classes.