The ascension of King Chulalongkorn (Rama V) to the throne in 1868 ushered in a Golden Age not only for muay but for the whole country. Muay progressed greatly during the reign of Rama V as a direct result of the king's personal interest in the art. The country was at peace and muay functioned as a means of physical exercise, self-defense, recreation, and personal advancement.

After the occurrence of a death in the ring, codified rules for Muay Thai were drawn up. These included the rules that the fighters should wear modern gloves and cotton coverlets over the feet and ankles. It was also around this time in the 1920s that the term Muay Thai became commonly used while the older form of the style was referred to as Muay Boran.