November 1st was once called All Hallows Day so October 31st was called All Hallows Eve which over time shortened to Halloween.
During Samhain superstitious country folks would disguise themselves with animal skins and masks made from sailcloth or linen. In costume they would go out side and make noise in effort to ward of evil spirits
Before the modern pumpkin lantren, turnips were used. In ancient Ireland, revelers would hollow out large turnips, potatoes and beetroot and carve them into demons faces to frighten away spirits