Authorities made the gruesome discovery while cleaning a remote cemetery in Mukdahan, Thailand, near the border with Laos.
The skin, found hanging off the dead man's skeleton, was covered with tribal bamboo tattoos.
The artwork is believed to have been inked as part of an ancient black magic spell was hoped to make the skin inpenetrable.
But in a cruel twist, it may have been the 'spell' that killed him, according to a Thai archaeological organisation.
"The skin has a lot of tattoos and it hasn't gone rotten. The spell to protect him and make him strong prevented the operation and then after he died stopped his skin from rotting."
The skin had been inked with Sanskrit writing and pictures of a tiger
The reason the skin had not rotted is not clear, but the discovery excited more superstitious Thais.
"This is amazing," Suriya Rachatawet said. "It shows that magic spells really do work."