Wikipedia
The alvars, also spelt as alwars or azhwars (āḻvārkaḷ , ‘those immersed in god’) were Tamil poet-saints of South India who espoused bhakti (devotion) to the Hindu god Vishnu or his avatar Krishna in their songs of longing, ecstasy and service. They are venerated especially in Vaishnavism, which regards Vishnu or Krishna as the Supreme Being.
Many modern academics place the Alvars date between 5th century to 10th century CE, however traditionally the Alvars are considered to have lived between 4200 BCE - 2700 BCE. Orthodoxy posits the number of alvars as ten, though there are other references that include Andal and Madhurakavi Alvar, making the number twelve. Andal is the only female saint-poet in the 12 Alvars. Together with the contemporary sixty three Shaiva Nayanars, they are among the most important saints from Tamil Nadu.
The devotional outpourings of Alvars, composed during the early medieval period of Tamil history, helped revive the bhakti movement, through their hymns of worship to Vishnu and his avatars. They praised the Divya Desams, 108 "abodes" (temples) of these Vaishnava deities. The poetry of the Alvars echoes bhakti to God through love, and in the ecstasy of such devotions they sang hundreds of songs which embodied both depth of feeling and felicity of expressions. The collection of their hymns is known as Divya Prabandha. The Bhakti literature that sprang from Alvars has contributed to the establishment and sustenance of a culture that broke away from the ritual-oriented Vedic religion and rooted itself in devotion as the only path for salvation. In addition they helped to make the Tamil religious life independent of a knowledge of Sanskrit. As part of the legacy of the Alvars, five Vaishnava philosophical traditions (sampradayas) have developed at the later stages.