The mountaintop of the Five Element Mountains is mystery and home to Demons and Devils. This is what the people of Silhae had always believed.
Even though the people believed in the Demon King, they worship him because they fear him. While some of the more ascetic group of believers believe in his other form the Holy Monkey of Enlightenment.
There have always been two aspect of the Demon Monkey.
There is that aspect of him as a fearsome Demon General attacking the Heavenly Court and there is the aspect of him becoming a Holy Monkey and attain awakening of the consciousness of all things.
But there is another reason why they called it mysterious and why they dreaded coming near the mountains.
It is because something unusual only happen on top of that mountaintop and nowhere else.
What is unusual?