TRADITION
The sanctuary rose out of ocean through the grace of penance of the god Brahma, who for long worshipped it in the world of gods and appointed the Sun God to attend to the daily worship of the God Sri Ranganatha. IKSHWAKU descendant of Sun, moved the sanctuary to capital Ayodhya, to venerate it. Later RAMA incarnation of Vishnu in the same dynasty presented the sanctuary to Vibhishana. While retuning to Lanka with the Vimana, Vibhishana reached Kaveri banks, where weary he laid the sanctuary. But when he was to go, could not lift it and the Vimana was fixed to the ground.
CHOLA KINGS
King Chola Dharma Verma ruling Kaveri area those days consoled Vibhishana, who is very sad. Lord Ranganatha declared solemnly that it was his desire to dwell on the sacred banks of Kaveri. To comfort Vibhishana, He promised to look after Lanka and rested facing south. Dharma verma built a temple round the sanctuary and founded a cult. But later this temple was floodded by rising waters of Kaveri and buried under sand for long. Dense forest hid it from site.Later once KILI, descedant king of Dharmaverma was resting under a tree in this forest area. He heard a parrot (KILl) repeating sanskrit verses meaning this is Temple of Srirangam area, Abode of Vishnu, Vaikunta and a temple can be seen. Kili chola started building new temple to to the west of the tree where he was resting. But Lord Vishnu appeared in his dream and showed him exact location where the actual temple lay invisible. Some say Kili chola followed KILI and discovered original temple. Kili chola later cleared forest, built streets, enclosures and flower gardens. He also strengthened banks of Kaveri river.
SILAPPADIKARAM and NAMMALWAR
The first written references to the temple appear in Silappadikaram sangam ERA III century / before CHRISTIAN ERA, and works Nalayirappirabandagal of NAMMALWAR. These are most GRAPHIC description of God of Srirangam, VISHNU reposing with Lakshmi on thousand hooded serpant known as RANGANATHA, Seshasayana Murthy, Anatha Sayana. A cosmic God whose concept goes back to period of RIG VEDA