Heavens are worlds (similar to the Six Paths Worlds, but at a much smaller scale) that the strong and powerful experts have created.
The Heavens have a Six Paths Reincarnation cycle, allowing their masters to control the Heavens' Six Paths Reincarnation and only reincarnate the initial inhabitants back inside the Heavens. This made it easier for their masters to monitor and ensure the purity and loyalty of the inhabitants in the Heavens.
These Heavens are paradises to the inhabitants.
*** Not to be confused with Heaven.