Sadeh in Persian means "hundred" and refers to one hundred days and nights left to the beginning of the new year celebrated at the first day of spring on March 21 each year. Sadeh is a mid winter festival that was celebrated with grandeur and magnificence in ancient Iran. It was a festivity to honor fire and to defeat the forces of darkness, frost, and cold.

Legends have it that King Hushang, the 2nd king of the mythological Peshdadian dynasty(Peshdad means to give the Law), established the Sadeh tradition.
It is said that once Hushang was climbing a mountain when all of a sudden he saw a snake and wanted to hit it with a stone. When he threw the stone, it fell on another stone and since they were both flint stones, fire broke out and the snake escaped. This way he discovered how to light a fire. Hushang cheered up and praised God who revealed to him the secret of lighting a fire. Then he announced: "This is a light from God. So we must admire it."
According to religious beliefs, Jashn-e Sadeh recalls the importance of light, fire and energy; light which comes from God is found in the hearts of his creatures.