The Demon Kingdom was located in the Demonic Impure Land.
The Demonic Impure Land was infamous for being the seventh forbidden area in Fantasia.
Although it was only the seventh and the weakest forbidden area, it still was a forbidden area that weak living beings dared not enter.
Those with weak will would be eroded by the demonic miasma constantly released by the land in the Demonic Impure Land.
For normal living beings in Fantasia, the demonic miasma would erode their mind and body and even affect their soul. It would cause them to demonize and lose their sanity.
However, for natural-born demons or those living beings born from a demon race, the demonic miasma was like a tonic for them.