A Thai boxer praying during the Wai Kru before match.Various forms of kickboxing have long been practiced throughout Southeast Asia. As with most countries in the region, the cultures of China and India have heavily influenced that of Thailand. Both countries had a hand in the developement of local martial arts. Indian boxing forms like Musti-yuddha are remarkably similar to Muay Thai and it is often said that every move in Muay Thai has a similar equivalent in Shaolin kung fu. Muay Thai's origin in Thailand can be traced back to its ancestor Muay Boran ("ancient boxing"). This was the form of unarmed combat probably used by Siamese soldiers in conjunction with Krabi Krabong, the weapon-based style [1]. The precedence Muay Thai and Muay Boran give to the kick is probably indigenous to Thailand and the surrounding area since Indian boxing as well as most southern Chinese styles use even low kicks sparingly. This may have come through the influence of the older Krabi Krabong wherein kicks are the dominant form of unarmed attack. Another influence from Thailand's weapon style can be seen in the pre-fight Wai Kru which is probably based on the sabre dance of Krabi Krabong. Neighbouring countries such as Cambodia or Myanmar also show signs of influence one way or the other. Eventually Muay Boran was divided to:

Muay Korat (Northeast) emphasized strength. A technique like "Throwing Buffalo Punch" was used. It could supposedly defeat a buffalo in one blow.
Muay Lopburi (Center region) emphasized movements. Its strong points were straight and counter punches.
Muay Chaiya (South) emphasized posture and defense, as well as elbows and knees.
Muay Pra Nakorn (North) emphasized speed, particularly in kicking. Because of its faster speed, it was called as well "Ling Lom" (windy monkey or Loris).
There is a phrase about Muay Boran that states, "Punch Korat, Wit Lopburi, Posture Chaiya, Faster Thasao. (หมัดหนักโคราช ฉลาดลพบุรี ท่าดีไชยา ไวกว่าท่าเสา)".

The practice of Muay Thai was later kept up largely by Buddhist monks who were the keepers and teachers of all arts both practical and spiritual. As every Thai man is compelled to live as a monk at least once in his life the art grew in popularity among common people, so much so that it was said that any man worth his salt would practice it. As well as continuing to function as a practical fighting technique for use in actual warfare, Muay Thai became a sport in which the exponents fought in front of spectators who went to watch for entertainment. This kind of muay contests gradually became an integral part of local festivals and celebrations, especially those held at temples. It was even used as entertainment to kings.

Eventually the previously bare-fisted fighters took to wearing lengths of rope wrapped around their hands and forearms. This type of match was called muay kaad chuek (มวยคาดเชือก). If both fighters agreed they might even glue pieces of broken glass to their gloves using resin or wet flour. Needless to say this was not common and is now banned.

Royal Muay

Muay gradually became a possible means of personal advancement as the nobility increasingly esteemed skillful practitioners of the art and invited selected fighters to come to live in the Royal palace to teach muay to the staff of the royal household, soldiers, princes or the king's personal guards. This "royal muay" was called muay luang (มวยหลวง).

Some time during the Ayutthaya Period, a platoon of royal guards was established, whose duty was to protect king and the country. They were known as Grom Nak Muay (Muay Fighters' Regiment). This royal patronage of muay continued through the reigns of Rama V and VII.