It is followed atleast from more than 2500 (from budhism period)..birth dates of ram and krishna... many religion came and many are the worst peak and many will die.. till today the Jambu dweepa people will beleive and carry their idols (Ram and krishna) together and forever..in other way ram and krishna are strong enough to stay in their sacred hearts with Love and Ethical human behaviour.. Atleast ram exists till the moon exists as it is ninth day in chaitra masa..morathan that both exists till the universe exists as they are evident by the star positions..not just Local evidences.
