From Elder Liu's description, Chu Mu found out that within the Immortal City, which in itself was an independent space, there was a more special independent world. This world sealed the super-disasters which had been ranked in the top ten in terms of strength for thousands of years!
White Language Demon Emperor Bai Yu had caused the strong ones from the three major powers fall, which definitely placed him within the top ten in thousands of years of history. Also, since he was forced to sleep for less than twenty years, the possibility of reviving him was extremely high.
The Sleeping World was a fully sealed space. A long time ago, a very powerful White Nightmare Demon guarded this place and forbade any creature from entering or leaving the Sleeping World.
