Where did Halloween come from? You might have been told that it holds its origins in the Mexican holiday, the Day of the Dead. But that is actually a completely separate holiday altogether, from the days it is celebrated to the traditions performed to its ancient origins in Aztec and other cultures.
Halloween originated in ancient Celtic culture. The Celts celebrated a festival called Samhain (pronounced SAH-win), during which people believed spirits appeared and walked about. deciding who among the living would die the following year. The Celts would dress in scary costumes to ward them off and left treats on their doorsteps for the spirits.
Samhain took place during the Celtic month, Samon, for which it is named. This time on the Celtic calendar can also be referred to as “Samonios”, marked by the late-October/early-November lunation.
Pope Gregory III marked November 1st as a day for honoring the saints in the eighth century, which contributed to the idea that the living could meet the dead during the harvest season. He called this day All Saints Day and the night before was called All Hallows Eve, now known as Halloween.