Is the Halloween film based on a true story?

(The short of a long story) Halloween has a very deep history. Many think Halloween is derived from Samhain (pronounced sow-in/en/un), the Celtic celebration of the end of summer and harvest; also believed to be the end of their calendar year (think of New Year's Eve today). Many stories/beliefs say Samhain was the day that the gates between the worlds of the living and the dead were open allowing the dead be among the living. The living would offer food, wine and gifts to help the dead in their journey (back?) across. Other stories/beliefs go into dressing up in crazy, often elaborate costumes to scare away the dead instead. Not sure exactly where the Trick or Treat comes from. Some stories are of Faeries disguising themselves as beggars, begging for food. By giving them food you got a Treat; by not giving, it was Trick. Other stories are the people doing strange things such as cross dressing from both sexes, moving live stock or structures to different places and of course playing tricks on each other.

The more popular ideal comes from early Euro-Christianity. By that point it was believed Samhain to be a mostly Pagan holiday; there's a lot of cross over between Celtic history and Paganism. The Christian church, being against Pagan belief, replaced the holiday. In 834 or 835 A.D., Pope Gregory IV moved All Saint's Day to November 1, which had originally been designated by Pope Boniface IV in 609 AD, to be on May 13th. While sanctioned by the Church, many of the common people still practiced the more Pagan/Celtic traditions like bonfires, parades, and costumes. All Saints Day was also known as All Hallows, or Hallowmas; thus Oct 31 became All Hallows Eve and later Halloween.