The origins of Halloween can be traced back to the ancient Celtic festival of Samhain. The Celts, who lived over 2,000 years ago in what is now Ireland, the UK, and parts of Northern France, celebrated their new year on November 1st. They believed that on the night between October 31st and November 1st, the boundary between the worlds of the living and the dead became blurred and ghosts of the dead returned to earth.