The regional origin of "magical clothing" may be traced to the golden age of the Ayutthaya Kingdom (1351-1767 CE), where warriors took to the battlefield clad in suea yant (shirts covered in magical yantras) meant to protect them. Slowly, over a period of time, these designs travelled on to the bodies of the warriors themselves, when they realized inking the skin was a more practical idea. And thus grew the sacred art of Sak Yant Tattoos. In order for the warriors to obtain the fullest protection and increased strength in battle, they would often have their bodies tattooed from head to toe with magic symbols to prevent knives and arrows from piercing their skin. This tradition continued in Thailand as late as the second world war, when in 1940, a special series of Suea Yant shirts were made to distribute to members of the Thai Military who were volunteering to fight in Foreign Struggles. Members of the French Military reported that they witnessed Thai soldiers being shot and knocked to the ground by bullets, and then immediately standing up again and going back into battle as if nothing had hit them. Because many of them were tattooed, wearing protective amulets, and also wearing vests covered with occult inscriptions, the French Military gave them the name of “Ghost Soldiers”.

The practiced religion of the Shan is rather a complex patchwork of Buddhist philosophy, folk practices, and animism within a Theravada Buddhist framework – or simply put, Folk Buddhism. Many Shans believe in ghosts and demons who haunt forests, graveyards, and other lonely places. The forest is believed to be inhabited by animals that are considered ferocious human ghosts, such as were-tigers. Buddhist monks can be called on to exorcise such ill-intentioned spirits, though the true magic practitioners, those who are experts in prescribing supernatural formulae, are called Sala in the Shan language. The word sala translates as a craftsperson or artisan, particularly in relation to the magic arts (similar to the Ajarn of Thai tradition). There are seven basic elements in the Shan belief systems. They are Theraveda Buddhist doctrine and practice, healing, sacred objects, spirits, astrology, cosmology and numerology. Salas who work within this belief system observe precepts and practice meditation. They create formulae for metta (loving kindness and compassion towards others) and respect, for luck in business or love, general forms of good luck, and wish fulfillment. They heal and protect against bad luck and apocalyptic events and a small minority deal in negative power that causes harm. In terms of healing, remedies are based on a premise that if a condition does not get better of its own accord, in a reasonable period of time, it is spirits and negative planetary forces that are at work. The remedy is a supernatural formulae composed of yantra - meaning a figurative illustration or a magic diagram. A second component is an incantation or "spell" (called a khatha in Tai; Kata in Thai). This is devised to empower the yantra. The third component is a text of instructions stating how, where, and when a yantra and khatha should be activated. Some supernatural formulae contain a high proportion of illustrations and diagrams while others are almost entirely devoted to text. Supernatural formulae is often formatted in grids (magic squares) containing letters, numbers, syllables and phrases that  represent codes for incantations and spells. Numbers are calibrated from planetary systems, numerology, and Buddhist cosmology. Monks and lay sala invoke the power of Buddhism and the spirits.

Sources:

Conway, Susan. Tai Magic: Arts of the Supernatural in the Shan States and Lan Na, Bangkok, 2014

Jenx. The Thai Occult, Timeless Editions, 2018