The Yalda night or the night is the longest night of the year in the northern hemisphere of the earth. This night refers to the time between the sunset from December 30 to the dawn on the first day of the winter. Iranians and many other tribes celebrate Yalda's night.
We'll go to our elders at Yalda's night and spend the night together. On this night, we eat the watermelon and pomegranate, whose name is sticking to this night.
Of course there are many snacks for guests: nuts, rice (roasted rice), all kinds of fruits, sweets, and...
They will have a ceremony for newly-wedded brides and they will bring different fruits and ... for them, which can be found below. 
On this great night, the family opens the book of Hafiz's poetry (one of the greatest mystical poets of Iran) and reads for the gathering, and runs Yalda's night.
