Ancient Welsh festival
Calan Gaeaf is the name of the first day of winter in Wales, observed on 1 November. The night before is Nos Galan Gaeaf or Noson Galan Gaeaf, an Ysbrydnos when spirits are abroad. Traditionally, people avoid churchyards, stiles, and crossroads, since spirits are thought to gather there. The term is first recorded in literature as "Kalan Gayaf" in the laws of Hywel Dda.