From December to mid-January Mari Lwyd is celebrated. A giant skeleton horse head is decorated with lights inside the skull. The mane of the horse is made of colorful streamers, or holly and ivy. A white cloak falls from the skull. The horse skull is then put on a stick and carried from house to house as a part of an ancient horse ritual. The skeleton horse head symbolizes the pale horse (Mari Lwyd) which is thought to be able to pass to the underworld. It is thought to bring luck and expel evil. If you let in Mari Lwyd they will eat food and drink ale and when leaving Mari Lwyd will wish everyone a happy New Year.

     The first recorded mention of Mari Lwyd comes from 1800, in a book titled ‘A Tour through Part of North Wales’ by J. Evans. This old tradition is celebrated in Great Britain in Southern Wales. Although the book states North Wales, it is more associated with Southern Wales. Mari Lwyd was thought to be have originated from Celtic Mythology. Supposedly Mari Lwyd was Grey Mary and is pre-Christian or Pagan. The horse apprentaly allowed Mary and Joseph to have shelter in the stables.

https://www.horniman.ac.uk/story/the-mystery-of-mari-lwyd/#:~:text=The%20first%20recorded%20mention%20of,from%20isn’t%20entirely%20clear.

https://rhinwedd.cymru/blogs/news/the-story-of-mari-lwyd#:~:text=What%20does%20Mari%20Lwyd%20mean,to%20pass%20to%20the%20underworld.