In the 16th century, Muay Thai was included in military training. At that time, those combat techniques allowed the Thai army to push back the Burmese.  

Muay Thai reached its zenith of popularity in the 18th century under the reign of Pra Chao Sua, who was known for his ferocity as a Muay Thai fighter and his strength. Pushed by the desire of the sport and challenges, he travelled anonymously around his kingdom to dare any Muay Thai fighter to beat him. He imposed Muay Thai training to his army. this quickly became the hobby of the Thai people.

Muay Thai is a figting sport, wich is very complete. For it's efficiency. It's even taught to the police and army. Every punch, kick, knee and elbow are allowed anywhere on the body (except the genitals and the neck). On top of these techiques, you are allowed to grab, throw and do body to body. The most effective weapons in Muay Thai are the elbows and the kicks, by kicking several times you adversary legs, you will destroy his support. In muay Thai you aren't allowed to hit your adversary on the ground, because he's in an inferior position.  

In Thaïland and Switzerland, you're allowed to use your elbows in competitions, but in the rest of the world, they are only allowed in professional fightsif the fighters, the managers and the organizers agree. Muay Thai develops the cardio-vascular system, the muscles, the coordination, flexibility and many fighting techniques. You ca do it at any age.