The ancient Persian autumn festival associated with harvest, light, and the god Mithra was Mehregan.
Mehregan is a traditional Iranian festival linked to Mehr, a name connected with Mithra and with concepts such as friendship, affection, and covenant. It is celebrated in autumn and has historically been associated with the harvest season. In the Zoroastrian calendar, the festival is connected with the month of Mehr and the day named Mehr.
Historical accounts describe Mehregan as one of the important festivals of pre-Islamic Persia. It was traditionally marked with decorated tables, seasonal produce, flowers, incense, and ceremonial foods. The festival’s themes include gratitude, abundance, light, and social harmony.
Mehregan is often confused with Nowruz because both are major Iranian seasonal festivals. Nowruz marks the spring equinox and the beginning of the Persian New Year, whereas Mehregan is an autumn festival. Yaldā, another well-known Iranian observance, is associated with the winter solstice rather than the harvest.