The Dark Regions, the most mysterious place of the Middle Realm that was also the power that was built single-handedly by the Dark Emperor. Before the Dark Emperor had appeared, there was no Dark Regions in the Middle Realm. Only until the Dark Emperor had demonstrated his power did the Dark Regions appear before everyone in the Middle Realm and had quickly became the most powerful force.
It was only...
No matter if it was before the appearance of the Dark Emperor or after his "fall", the location of the Dark Regions had always been a huge mystery. Apart from the people of the Dark Regions, no one knew where it was. Even though the Upper Realm had searched the entire Middle Realm, the Dark Regions seemed as if it did not even exist as it was hidden away from the eyes of everyone.
When the Rui Lin Army entered the Dark Regions for the first time, they then knew why the Dark Regions could avoid detection and could stay hidden away.