The Alvars are considered the twelve supreme devotees of Vishnu in Sri Vaishnavism, who were instrumental in popularising Vaishnavism in the Tamil-speaking regions.The Alvars were influential in promoting the Bhagavata cult and the two Hindu epics, the Ramayana and the Mahabharata.The religious works of these saints in Tamil, and their hymns, are compiled as the Naalayira Divya Prabandham, containing 4000 verses, and the 108 temples revered in their hymns are classified as Divya Desams.The verses of the various Alvars were compiled by (824 - 924 CE), a 10th-century Vaishnavite theologian, who called it the "Dravida Veda or Tamil Veda". The songs of the Prabandam are regularly sung in various Vishnu temples of South India, daily, and also during festivals.
The legendary birth of the Alvars is traced to an event in the mid-Dvapara Yuga, due to a heated debate between Vishvakarma (the divine architect of the gods) and Agastya (a sage) about the superiority of the Sanskrit or the Tamil language.In the midst of this debate, Agastya gets furious, which makes him curse the former that at some point of time, one of his pieces of architecture would be destroyed (a contemporary to Gandhari's curse to Dvaraka) and would never be recovered. (Some sources say Agastya curses Vishvakarma for Sanskrit to lose its fame, as the curse became true in the present Kali Yuga).Enraged, Vishvakarma curses Agastya in turn that his most favourite language (Tamil) would be tarnished in the future. Agastya, feeling guilty regarding his actions, is offered a divine vision of Vishnu, who promises him that Tamil would regain its prestige, and that a Tamil Veda would emerge.
After the Kurukshetra war, the decline of Dvaraka, and Krishna's death at the hands of the hunter Jara, Krishna, as Vishnu resumes his residence at his abode in Vaikuntha, sowing the seeds of the Kali Yuga. He becomes worried about the people of the Kali Yuga. His attributes, such as the Sudarshana Chakra and the Panchajanya, enquire the reason for his anxiety, and he confides his fears to them. The Sudarshana Chakra suggests that he slice the head of all the people who refuse dharma, to which Vishnu smiles and refuses. Vishnu decides that his amshas (parts of his identity) would be incarnated as humans on earth, and teach them the path of righteousness and devotion to him. These amshas happily accepted their birth as the twelve Alvars, aligning with the boon given to Agastya, and also became a role model for the human beings who came later in the Kali Yuga.
Fulfilling the promise that Vishnu made to Agastya, Nammalvar (Regarded to be an incarnation of Vishvaksena) is credited for converting the Rigveda to 100 poems called the Tiruviruttam, the Yajurveda as Thiruvarshiyam, and the Sama Veda as Tiruvaymoli in 1000 verses (poems).