Informant38

History of Korean Martial Arts After the Korean liberation from Japan (August 15, 1945), Korean martial arts (i.e. "moo-yae" or "moo-sool") spread rapidly throughout the country. Classical Korean martial art techniques, which had been hidden, one by one surfaced and became publicly known. The reason for this rapid public disclosure of secret arts stems from the rivalry that developed between each proponent of some individual martial art form. That is, individual masters of their own particular martial art techniques tried to show theirs to be the "superior" Korean martial art.

However, the majority of these martial art skills to surface at this time were not organized systematically and were nothing more than individual techniques. Hence, after a brief flurry of activity, many of these arts ended up fading out of sight again.

Although these classical Korean martial arts were highly-developed, I suspect the reason for their disappearance were either because of the difficulty of adapting them practically to the needs of the modern society, or because they weren't something which could be made into sports.