Halloween costumes are costumes worn on or around Halloween, a festival which falls on October 31. An early reference to wearing costumes at Halloween comes from Scotland in 1585, but they may pre-date this. There are many references to the custom during the 18th and 19th centuries in the Celtic countries of Scotland, Ireland, Mann and Wales. It has been suggested that the custom comes from the Celtic festivals of Samhain and Calan Gaeaf, or from the practise of "souling" during the Christian observance of Allhallowtide. Wearing costumes and mumming has long been associated with festivals at other times of the year, such as on Christmas. Halloween costumes are traditionally based on frightening supernatural or folkloric beings. However, by the 1930s costumes based on characters in mass media such as film, literature, and radio were popular.