Merchandising groups in the past had the custom of taking the sacred relics of the Buddha as their heritage, for their protection, righteousness and meritorious deeds and for the protection of the sight of God.There was a highway station that had fallen through the area to the inner colonies. It was called Rathna welimangodella. Merchants used to worship their sacred relics keeping under a kirihadu tree on that place.
After a few days of trading in the area a group of merchants set out on a commercial tour and looked at the sacred relics and the sacred tree. It is revealed that all sacred things and the tree have gone down into the earth shinning few branches like a silver tree.
They were so impressed by this miraculous event that they reported to king Mahananga the king of the province. Then this was informed to his brother king Devanampiyatissa (A.D 247-207) on the advice of king Mahanaga.
The king, delighted with the enlightenment of the Buddha and examined the matter and made a large stupa around the place where the sacred relics had sunk.