The Battle Maniac Asura spread many martial arts in the Mortal Realm. Although those martial arts were considered magic power, some exceptionally talented individuals somehow twisted the magic power, turning it into normal yet formidable martial arts.
Moreover, when dealing with other Supreme Demons, whether it's magic power or martial arts of the Righteous Path, any martial art that could defeat a Supreme Demon was considered good. Because of the Battle Maniac Asura's preferences, many Supreme Demons had been tricked and ended up sealed in a place without daylight.
The martial arts that the Battle Maniac Asura had previously left for Zheng Yichen weren't left on purpose. It was purely out of old habit. In this world, whether one cultivates spells or martial arts, no one lives past three hundred years old. That age is considered the 'limit' for the human race.
Unless one chooses not to be human.
