By: Mir M.Hosseini
The oldest record of the Yalda night celebrated by Iranians throughout the world dates back to a calendar observed by Iranians who left for India after the Arab invasion. Yalda is the longest night of the year and the next day is believed to be the birth day of the sun also called Daygan. On the Yalda night, Iranians used to stay awake all night till the dawn and normally the following day: Dec,22 was a holiday. Even little lies are considered great sin on Daygan. Daygan is also the day of equality because on this day the king and nobles were to dress just like ordinary people so as not to be recognized in the crowd and nobody was supposed to give order on Daygan. Many Christian, Jewish and Muslim customs have root in Mithraism which was the oldest religion practiced in human society. An old tradition that would serve as a green movement today was that each Iranian pledged to plant a cedar tree during the year.