Thirumalisai Alvar is a tamil mendicant-saint revered in the Shri Vaishnavism school of south India between the 4th to 9th century CE in Tondai Nadu [now called Kanchipuram and Tiruvallur districts]. There are only little historical records of this alvars. The legend of this saint Devotees of Shri Vaishnavism say that he was the incarnation of Vishnu's disc, Sudarshana. He belonged to Paraiyar caste, he proclaimed that he was "not of the 4 castes" (Brahmin, Kshatriya, Vaishya & Shudra) in one of his couplets as he was considered (Avarna) untouchable and casteless person.

   He had the access and resources to learn about various religions because in one of his couplets he says "After my futile efforts to know the supreme principle through Jainism, and Buddhism I am blessed by Shriman Narayana to take refuge at the Lotus feet of Shri Devi and have escaped all problems and misfortunes since then".

   There is also evidence in his couplets that show that he asked God to help reveal their ignorance to them. Legend also says that when he displeased the pallava king and was banished, he asked the God from the Temple, Yathotkari, to leave with him. Vishnu is said to have rolled up the snake Sesha like a matress and left with him

   Source : http://en.wikipedia.org/wiki/Thirumalisai_Alvar