Buhdy asked me to repost this essay, so here it is again.
Prior to Theravada Buddhism, the Burmese were animists who worshiped a series of nature spirits called Nats. The term Nat derives from the Pali-Sanskrit, natha, meaning lord or guardian.
There are 37 officially recognized Nats (inside Nats), each with its own history. The Nats are spirits of natural forces, such as water, wind, stones and trees and take many guises. All Nats are ghosts or spirits of heroes. There are many lesser nats (outside Nats) that are characterized as mischievous when they are disturbed.
…Some were martyrs, people who had been betrayed or had suffered a premature and frightful death. One had died of diarrhea and was reputed to inflict that on those who displeased him.
Regardless of their origins, they were easily disturbed, given to making a fuss when they were not treated with respect.
~Amy Tan, Saving Fish From Drowning, a novel combining Myanmar politics, Burmese superstition and spirituality, plus a touch of humor.