Samhain is believed to have Celtic pagan origins and there is evidence it has been an important date since ancient times. Some Neolithic passage tombs in Ireland are aligned with the sunrise around the time of Samhain. It is mentioned in some of the earliest Irish literature and many important events in Irish mythology happen or begin on Samhain. It was the time when cattle were brought back down from the summer pastures and when livestock were slaughtered for the winter. As at Bealtaine, special bonfires were lit. These were deemed to have protective and cleansing powers and there were rituals involving them. Like Bealtaine, Samhain was seen as a liminal time, when the boundary between this world and the Otherworld could more easily be crossed. This meant the Aos Sí, the 'spirits' or 'fairies', could more easily come into our world. Most scholars see the Aos Sí as remnants of the pagan gods and nature spirits. At Samhain, it was believed that the Aos Sí needed to be propitiated to ensure that the people and their livestock survived the winter. Offerings of food and drink were left outside for them. The souls of the dead were also thought to revisit their homes seeking hospitality. Feasts were had, at which the souls of dead kin were beckoned to attend and a place set at the table for them. Mumming and guising were part of the festival, and involved people going door-to-door in costume (or in disguise), often reciting verses in exchange for food. The costumes may have been a way of imitating, and disguising oneself from, the Aos Sí. Divination rituals and games were also a big part of the festival and often involved nuts and apples. In the late 19th century, Sir John Rhys and Sir James Frazer suggested that it was the "Celtic New Year", and this view has been repeated by some other scholars.
In the 9th century AD, Western Christianity shifted the date of All Saints' Day to 1 November, while 2 November later became All Souls' Day. Over time, Samhain and All Saints'/All Souls' merged to create the modern Halloween. Historians have used the name 'Samhain' to refer to Gaelic 'Halloween' customs up until the 19th century.
… In parts of southern Ireland during the 19th century, the guisers included a hobby horse known as the Láir Bhán (white mare). A man covered in a white sheet and carrying a decorated horse skull (representing the Láir Bhán) would lead a group of youths, blowing on cow horns, from farm to farm. At each they recited verses, some of which "savoured strongly of paganism", and the farmer was expected to donate food. If the farmer donated food he could expect good fortune from the 'Muck Olla'; not doing so would bring misfortune. This is akin to the Mari Lwyd (grey mare) procession in Wales, which takes place at Midwinter. In Wales the white horse is often seen as an omen of death. In some places, young people cross-dressed In Scotland, young men went house-to-house with masked, veiled, painted or blackened faces, often threatening to do mischief if they were not welcomed. This was common in the 16th century in the Scottish countryside and persisted into the 20th. It is suggested that the blackened faces comes from using the bonfire's ashes for protection Elsewhere in Europe, costumes, mumming and hobby horses were part of other yearly festivals. However, in the Celtic-speaking regions they were "particularly appropriate to a night upon which supernatural beings were said to be abroad and could be imitated or warded off by human wanderers".
photo: A Mari Lwyd, the Welsh equivalent of the Láir Bhán
see also: what next: BBC Archive - #OnThisDay 1948: The villagers of Abbots Bromley | the weird and wonderful world of English folk customs