The Celts of ancient Ireland believed Samhain was a night when the barrier between worlds was thin, the dead could cross over, and if you didn't disguise yourself, evil fairies might spirit you away. Throughline The Dance of the Dead (2021) The Dance of the Dead (2021) Listen · 50:20 50:20 Enlarge this image toggle caption Illustration by Hokyoung Kim Illustration by Hokyoung Kim Long before it was a sugary moviefest, the Halloween we know was called Samhain. The Celts of ancient Ireland believed Samhain was a night when the barrier between worlds was thin, the dead could cross over, and if you didn't disguise yourself, evil fairies might spirit you away.