The first people to celebrate what became Halloween were the ancient Celtic people of Western Europe, particularly the Celts living about 2,000 years ago. They celebrated a festival called Samhain on October 31, marking the end of the harvest and the beginning of the darker half of the year. During Samhain, they believed the boundary between the living world and the spirit world was thin, allowing spirits to pass through. To ward off harmful spirits, people lit bonfires and wore costumes and masks. This Celtic festival is the origin of many Halloween customs seen today.
The holiday evolved over time as Romans introduced their own festivals during their conquest of Celtic lands, and later, Christianity incorporated the celebration of All Saints' Day (All Hallows) on November 1, with Halloween originally being All Hallows Eve. Irish and Scottish immigrants brought these traditions to America in the 19th century, where Halloween further developed into the modern holiday.
