Suh InhyukSuh Inhyuk, a researcher of Korean martial arts, divides Korean martial arts into three groups, classified by their use:
- Sado Moosul (private or folk martial arts). These styles are related to sport and competition.
- Pulsa Moosul (Buddhist martial arts). These styles were practiced in Buddhist temples and were dedicated to moral self-improvement and spiritual-physical development.
- Kunjoon Moosul (court martial arts). These styles were used to train the military and had an accent on weapons.
The earliest known names for Korean martial arts that formed the foundation of Taekwondo were Subak or Taekkyon. In researching writings about ancient Korea, it is difficult to differentiate between these two ancient martial arts. The first references to Subak, claimed to be the predecessor of Taekkyon, are found in the Koryosa (History of Koryo) circa 1147. The first reference to Taekkyon is found in Chaemulbo, a book written by Yi Song-gi during the reign of King Chongjo (1776-1800). Many historical references consider the two terms synonymous since there is no clear dividing line between the two. Subak was the older of the two arts and Taekkyon built upon it by adding more foot techniques. Over the centuries, Subak has been called Subak-hi, Subak-ki, and Subyeokta; while Taekkyon has been known as tak-kyeon, gak-hi, gak-sul, and bigak-sul. Many other fighting styles developed in ancient Korea, such as Kannyok or Subak-chigi, Charyok, Yu-sul, and Oren-kwon but the most original and "most Korean" of them was Taekkyon. The name Taekkyon was always written using the Korean alphabet, while other style names were written using Chinese hieroglyphs.