But I must disagree with the "has nothing to do with" part. There is more
relationship between the two events than accidental concurrent dates.
Halloween occurs when it does because of All Saint's Day / All Souls Day and
is celebrated with costumes and jack-o-lanterns and going house-to-house
because those things have come down to us from how All Saint's Day / All
Souls Day were observed in the cultures of the Celtic nations. American
pumpkins make better lanterns than British turnips did. Because two cultures
have developed celebration of the same religious holiday in different ways
doesn't mean they have nothing to do with each other.