When and from where Nayanars and Alwars came into being ?

A new kind of bhakti in south India was led by Nayanars and Alvars in the seventh to ninth centuries .The Nayanars were the saints devoted to Shiva and the Alvars were saints devoted to Vishnu. They came from all castes including those considered “untouchable” like the Pulaiyar and the Panars. They were sharply critical of the Buddhists and Jainas and preached ardent love of Shiva or Vishnu as the path to salvation.  The Nayanars and Alvars went from place to place composing exquisite poems in praise of the deities enshrined in the villages they visited, and set them to music.