- Also see: Mountains and Seas
The Vast Expanse is the universe in which the Mountain and Sea Realm resides in. It has locations that have yet to be discovered by cultivators, only someone with Transcendent power can explore the Vast Expanse without any problem. It is also known as the Vast Expanse Arcane Pocket Realm by the people in the Vast Expanse Cosmos.
With Meng Hao replacing Allheaven as the ruler of the starry sky he formally renamed the Vast Expanse to the Mountains and Seas.
An unknown amount of time after the creation of the Vast Expanse which was, while it was still chaotic and had yet to form its own will, Allheaven came along becoming the ruler of the vast expanse.
After Meng Hao replaced Allheaven as the ruler of the Vast Expanse, he renamed it the starry sky of the Mountains and Seas. 
- Innumerable remote planets and asteroids
- Vast Expanse School
- Ice-Fire Realm
- Green Coffin Vortex
- Mountain and Sea Butterfly (no longer exists)
- Ninth Mountain and Sea
- 33 Heavens (destroyed)
- Paragon Immortal Realm (destroyed)
- 3000 Lower Realms (destroyed)
- Seven Soils Realm (destroyed)
- Paragon Demon Realm (destroyed)
- 3000 Greater Demons (destroyed)
- Devil Realm Continent (destroyed)
- Immortal God Continent (destroyed)
- Mountain and Sea Realm (destroyed)