Earlier when Jun Wu Yao left the Upper Realm, he had been setting up the reversal array in secret. The title "Dark Emperor" and the Dark Region were just a camouflage he used to distract the Upper Realm. All the while, the Lower Realm was the actual place where he carried out his real plans. Only by making use of the unique features of the environment in the Lower Realm, they would be able to constrain the movement of the Upper Realm.
He had been planning and organizing everything for a thousand years. Besides the Night Regime, another force was left in the Lower Realm by Jun Wu Yao - the Ghost Army.
The Ghost Army had never participated in any battle and they would never expose any of their specialities in public. Since the establishment of many countries in the Lower Realm, they had been building up the Ghost Cities surreptitiously as a cloak to set up the reversal array.
