Samhain () was the first and most important of the four quarter days in the medieval Gaelic calendar and was celebrated on 31 October – 1 November in Ireland, Scotland and the Isle of Man. A kindred festival was held at the same time of year by the Brittonic Celts, called Calan Gaeaf in Wales, Kalan Gwav in Cornwall and Kalan Goañv in Brittany; a name meaning "first day of winter". For the Celts, the day ended and began at sunset; thus the festival began on the evening before 7 November by modern reckoning (the half point between equinox and solstice). Samhain is mentioned in some of the earliest Irish literature. The names have been used by historians to refer to Celtic Halloween customs up until the 19th century, and are still the Gaelic and Welsh names for Halloween.