Thiruppaan Alvar was born in Purthurmadhi year, Kaarthigai month, on a Wednesday in the Rohini Star (Natshatram) in the small village of "Alagapuri" near Shrirangam in the 8th or 9th century C.E. He was born in "Paanar Cheri". Paanars are a community of musicians and traditional songmakers who are capable of moving their audiences to states of ecstacy and bliss. Tradition goes that because of these skills they had an influence over the Devas (demigods) and Sages. Despite this, the Paanar community were considered as outcastes and were victims of the social dynamics of their times.

   It is said that Alvar is the amsam (significant) of the small mole (tradition has it that all alvars are avatars of some part of the Lord), called as "Shrivatsam" on the chest of Shriman Narayanan. Having a veena in his hand, he was always to be seen singing the glories of Shri Vishnu. He was soon famous in and around these tamil lands of Southern India. His skills as a bhakti musician and his abilities to express and invoke bhakti amongst his listeners, drew audiences from afar. He was soon to be known as "Paanar perumal".

   One of the strictures on outcastes was that they were not to come anywhere near the Cauvery river , considered scared and pure by the people of the region. Following this stricture Paan Perumal did not come anywhere near the Kaveri river, but mostly stood alongside its banks facing the Shrirangam Temple and sung his praises to the Lord.

   The following incident in the life of the Alvar , is considered a "divine play" lila of the Lord. The supreme bhakti and devotion that Paanar held within him had to be brought out and explicated as an example of devotion to the Supreme. As is the wont of the Lord, the other bhaktas of the world had to be made aware of such a soul in their midst.

   One day, a devout Brahmin in the service of the Temple, by name Loka Shaaranga came to the river for taking water for use in the Temple. He motioned to Paanar to move away. But, Paanar was so engrossed in the rhapsody of his music that he did not hear this. Loka Sharanga threw a small stone in his direction to shake him up. But, the stone accidentally fell on the forehead of Paanar and it started to bleed. Paanar quietly retired.

   Unaware of the injury caused, Loka Shaaranga returned to the Temple. He was taken aback on seeing blood oozing out from the forehead of the image of Lord Ranganatha. But, none could connect the two incidents. That very night, the Lord appeared in the dream of Loka Shaaranga and commanded him to fetch Paanar to the Temple the next morning. Accordingly, Loka Sharanga requested Paanar to come to the Temple. But, Paanar referring to his low birth declined even to set foot on the holy earth of Shrirangam lest he pollute the holy place. When he was told of the Lord's commandment, Paanar was beside himself and was lost in a deep trance. Loka Shaaranga said that if that were his objection Paanar could get on his shoulders and he offered to carry Paanar to the Temple. Loka Shaaranga carried Paanar who was in a state of trance. This also earned the Alvar, the sobriquet, Munivaahanar (the one astride a priest).

   When they reached the Sanctum Sanctorum, Paanar experienced the bliss of Ranganatha and composed the 'Amalan Adhipiraan' a poem describing the beauty from head to foot of the Lord in 10 verses and laid his life at the feet of the Lord. The poem is considered to be sweeter than even the 'sound of music' of the Veena.

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