The following history of Muay Thai is re-printed from a hand-out distributed by Ajarn Chai Sirisute at the 2000 Oregon Muay Thai Camp.
Muay Thai started way back in the medieval ages when wars were fought with bows and arrows, swords, and pikes.  And in hand-to-hand combat arms, legs, knees, and elbows were also used as weapons.  This sport which was included in military training was made famous by King Nareusan 1560 A.D.  During one of the many battles between Burma and Siam he was captured.  The Burmese knew of his prowess as the best unarmed fighter in the realm and gave him a chance to fight with their best for his freedom.  Upon his return to Siam he was hailed as a hero and Siamese-style boxing, as it was called then, was soon recognized as a national sport.  Boxing in this style reached its zenith of popularity about two hundred years ago, i.e., in the reign of Prachao Sua (King Tiger), when it was indulged in by all classes of the population.
From those days up until the early part of this century, the fighters, particularly those in provinces, used horsehide strips and later help in lieu of gloves.  It was also a practice at one time to grind pieces of glass into the help if both contestants agreed.  Since these practices were obviously dangerous to the fighters' health, regular boxing gloves were introduced about 50 years ago and have been used ever since. 
To the Thais, Muay Thai is regarded as a prestigious national sport.  Thai boys will in one or another way, intentionally or unintentionally, learn how to box Thai style.  Even Thai girls will know enough of the basic principles and to be able to use it for self-defense when necessary.
Muay Thai, called Thai Boxing by foreigners, is our national sport and is now getting more popular in many countries, especially in Japan where a large numer of young Japanese are now being trained to fight professionally.  But in Japan this fighting is called "Kick Boxing."  At present "Kick Boxing" is internationally known as a Japanese martial art.  Surely the true name, "Muay Thai" should be retained internationally as the Japanese terms Kendo, Judo, or Karate have been.
There is no [clear] evidence to show the time of origin of Thai-Style boxing.  It can only be assumed that Thai boxing existed since the Thai emigrated from the South of China.  [Further archaeological work needs to be done in this area, both in the Thai and English languages.]
The [Tai tribe] immigrants had to hide from attackers and met with resistance from local people.  In short, they had to fight endlessly for their survival.  By the time they managed to settle in the "Gold Promontory", the Thais had gone through to countless battles and many lives had been lost.  The ancient weapons consisted only of spears, swords, pikes or bows and arrows.  But in hand-to-hand combat weapons become clumsy, and elbows, knees, feet and fists became more practical.  This must have been extremely successful, as it was then developed into a form of martial arts used in battle, and this was the origin of Muay Thai.
When the Thais finally settled down and built a city, and extended their territory to become a large country, there was a need for an army to defend the country.  Soldiers in those days had to learn Muay Thai along with the use of traditional weapons.  Thus there was also the need for Kru Muay, or teacher of Thai boxing.  Various tactics for attack and defense were developed, called "boxing tactics".  Later, laymen began to take up this form of fighting, as a form of self-defense, and as a handy qualification to become a soldier, which would also lead to further advancement depending on their ability and talent.
During the Ayudhya period, which was a period of consecutive fighting against the neighboring countries of Burma, Cambodia and Vietnam, history records state that King Sri San Petch or Khun Luang Sorasak known as Phra Chao Sua (The Tiger King) often boxed incognito in various up-country temple fairs.  He is said to have been a skilled boxer, and enjoyed the sport so much that he often disguised himself thus in order to test his skill against villagers and thus became quite a legend in his own time.
When Ayudhya fell in 1767 A.D. many Thais became prisoners of War.  In 1774 the King of Burma held a festival to celebrate the Chedi containing the Bhuddha's relics in Rangoon, with various forms of entertainment and festivities.  This included a boxing display for the King by a Boxer named "Nai Khanom Tom" a prisoner of war from Ayudhya.  Pit against Burmese boxers, Nai Khanom Tom defeated 10 Burmese opponents in a row, and also became quite a legend.

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