The people of Thailand are as interested in their national sport, the art of Muay Thai, as people from the USA are about Baseball, or people from the UK are about football. Just because it involves fighting, don't dismiss it as a blood sport. Muay Thai is an ancient martial art, possibly one of the first, and has a noble past.
Evidence suggesting the age of Muay Thai is over 2000 years old, it has been practiced by the countries great kings and was once used as a art of defense from foreign attackers.
The people of Thai are that passionate about the sport that before the 1920's it was mandatory to learn the martial art in school. In the past Muay Thai's blood sport reputation has been well deserved. Until the 1930's very few rules and regulations where put in place. There where no rests between rounds, and protective gear wasn't widely used, with the exception being a groin protector, since kicks to that groin where allowed. Boxing gloves where introduced to create a safer spot in the late 1920's. Before that hand raps where sometimes used, often soaked in ground up glass and resin for optimal damage.
The punches, painful combination's, turn the fists into spears.The Roundhouse Kick can break vial bones and turns the leg into a devastating weapon. Elbows delivered to the face, or knees shoved into an opponents abdomen copies the motions of a large battle axe. Finally powerful front kicks can imitate a large variety of weapons.
In a professional match fights are five three minute rounds, with two minute breaks splitting each one up. Judging of a fight is done on a point scoring system, with whoever scoring most points in a round winning that round.
It should be noted that generally wins in the later rounds are given more wieght then wins earlier in the fight, since judges see the art of Muay Thai as a marathon, the winner being the best over all 5 rounds.
The winner is determined by a majority. Fights can also be won with a knockout, defined where the opponent can't continue to fight. A ritual you might see is the dancing before a muay Thia match, called the wai kru or the ram muay (Though these terms are used interchangeably, the word wai kru means a homage to a trainer.) The ram muay is a tradition to honor the supporters of the fighter and his deities, as well as giving both opponents the chance to warm up for the fight. Both opponents will walk around the ring with one arm over the top rope, 'sealing out' any 'bad spirits' saying a short prayer at every corner. They will then kneel down in the direction of each fighters birthplace, and then do a specific set of movements. Fighters can be largely superstitious and will wear a great many good luck charms, on the head and arms, when going into battle. The music you will hear is a live band, with the musicians closely watching the fight to speed up the pace of the music at interesting parts of the fight, or to egg the fighters on.