Answer: Samhain
Explanation: Halloween, as we know it today, has its roots in several ancient Celtic and Roman festivals. One of the most significant precursors to Halloween was the Celtic festival known as Samhain. Samhain was celebrated around 2,000 years ago in what is now Ireland, the United Kingdom, and parts of France.
Samhain marked the end of the harvest season and the beginning of winter. It was believed to be a time when the boundary between the living and the dead was thin, allowing spirits and fairies to roam freely. People would light bonfires and wear costumes to ward off these malevolent spirits. They also left food and offerings for these spirits.
Over time, as Christianity spread and merged with pagan traditions, Samhain evolved into the modern Halloween holiday, which incorporates elements of various ancient festivals and customs. So, Halloween didn't have a specific name 2,000 years ago, but the practices and traditions associated with it had their origins in ancient Celtic and Roman celebrations.