"As for why they rarely descend upon the Ancient Region!"
Immortal Emperor Yin-Yang gave a bitter smile. "There are three reasons."
"First, the Barrier itself is extraordinarily powerful. It is no simple wall, but an absolute forbidden zone woven by the World Will from the Origin Laws. It targets living beings and individuals with immense power. The stronger a being is, the more terrifying the resistance and attacks it faces when trying to cross. Fourth- or fifth-turn Immortal Emperors might be able to force their way through during a period when the Barrier is relatively weak, or at a particular fissure, but only at tremendous cost. Few could make it through, and those who did would usually arrive in terrible condition and need a long time to recover. For someone like me, who reached the ninth turn at my peak, the resistance would be even greater!"
"Second, the cost is too high for too little gain!"
Immortal Emperor Yin-Yang continued, "The powerhouses of the Primordial Region are focused on surviving and growing stronger in its harsh environment, and on resisting the internal Heavenly Punishment imposed by the World Will. That takes up most of their energy!"
"In their eyes, the Ancient Region may be poor in resources and mild in climate, but it does little to temper the strongest fighters, so its appeal is limited. Unless they have a specific goal, high-level Cultivators won't readily pay an enormous price to cross the Barrier. As for low-level Cultivators? They aren't even qualified to approach its edge."
"Third, there may be some kind of restriction or pact."
Immortal Emperor Yin-Yang looked thoughtful. "This is only my guess. The most powerful beings in the Primordial Region, such as its few ancient eighth- and ninth-turn emperors, use the Barrier to protect their territory from