The hills are located at the north-west of the Western Ghats and the westernmost edge of the Eastern Ghats. Thus this area supports a diverse flora and fauna in view of the various habitat types present. A wildlife sanctuary of was created around the temple on 27 June 1974, and enlarged to on 14 January 1987. The sanctuary derives its name Biligiri (white hill in Kannada) from the white rock face that constitutes the major hill crowned with the temple of Lord Ranganathaswamy (Lord Vishnu) or from the white mist and the silver clouds that cover these hills for a greater part of the year. An annual festival of Lord Vishnu, held in the month of April, draws pilgrims from far and wide. Once in two years, the Soliga Tribals present a 1-foot and 9 inches slipper, made of skin, to the deity in Biligiriranga Hills.