Ghosts and the supernatural is a deeply rooted belief in Thai culture, it’s origins are dated well before the introduction of Buddhism when in fact the religion, rather the beliefs were devotion of animism.
Animism (from Latin anima "soul, life") is a philosophical, spiritual idea that souls or spirits exist not only in humans but also in animals, plants, rocks, natural phenomena such as thunder, geographic features such as mountains or rivers, or other entities of the natural environment.