The famous Dragon Cave of Jinyun Country was at the center of Hidden Dragon Island. If one looked down from an airship, one would see the entrance of Dragon Cave was an underground cave that had an area of over 10 sq km.
Although there were already various pieces of evidence that there was nothing beyond the stars before the Catastrophe, humans during that age were basically under the rule of demons who masqueraded as humans. In order to better manage the people, the ruling demons influenced them to focus on mutual destruction. Therefore, people were forbidden to be too curious and explore this world. The ruling demons fabricated various lies about the world to firmly constrain people's thoughts and free will. Each person who entered school would be constantly brainwashed by all kinds of lies fabricated by the demons since they accepted education.
