This is an example of the outdated technique of self-preservation. It works by oneself staying in a deep meditation for 3 weeks while fasting, while his body deteriorates and becomes preserved due to mummification toxins.
This case is extremely interesting for monks, as they believe that due to the lotus position he was found in, he may be in a preserved meditation state called the 'tukdam state', meaning that he will have achieved the highest possible form of Enlightenment.
found in lotus vajra position, a meditation state
Yalım, D. (2017, January 14). This 200 Mongolian Mummy Is Unlike Any Other-There’s A Chance It’s Still Alive. Retrieved January 27, 2017, from http://bayart.org/this-200-mongolian-mummy-is-unlike-any-other-theres-a-chance-its-still-alive/