Simollanghan is crossing the border or frontier of a village or a place. In ancient times, kings used to cross the frontier of their kingdom to fight against their rivals or neighbor kingdoms. They used to perform Ayudha Puja on Dasara and begin the war season.
On Dasara, people cross the borders of their places (Simollangan) and collect the leaves of Apta tree and exchange among their friends and relatives as gold. People worship Shami tree on this day.