"Master, what exactly are the human race's Four Great Grotto-Heavens?"
On the Spirit Boat heading to the Teleportation Array plaza of Qingyang Immortal City, Zhou Ling asked his master.
There had been little time in the secret realm earlier, so he had not questioned Golden Soul Burning Heaven Flame in detail.
Now that they had time, he curiously asked his master about it.
He had originally believed that the Dao Alliance was already the most powerful force among humanity.
He had not expected the existence of the Four Great Grotto-Heavens.
Moreover, from Golden Soul Burning Heaven Flame's words, the Dao Alliance was not the strongest among the Four Great Grotto-Heavens.
But it should not have been the weakest, either.
Thus, he could roughly gauge the strength of the human cultivators from the other three Great Grotto-Heavens.
After all, from what he understood—
Among the Dao Alliance's nine supreme beings, all were great cultivators at the Void Refinement level.
Yet among the hundreds of Immortal Cities in the entire Qingyang Immortal Domain, there were no Void Refinement cultivators.
The highest cultivation was merely Soul Transformation, and there were no more than a handful of Late Soul Transformation cultivators.
Like the Wang Family ancestor, whose cultivation was Mid Soul Transformation, he was already considered a high-level powerhouse in the Qingyang Immortal Domain.
This also showed that the Qingyang Immortal Domain was far weaker than the Tianxia Immortal Domain.
Still, that was only natural. After all, the Tianxia Immortal Domain stood first among the Dao Alliance's nine Immortal Domains.
Its strength was surely beyond comparison with the other Immortal Domains.
"The Four Great Grotto-Heavens?"
At the side, Wang Qingshang also revealed a puzzled expression.
It seemed that she, too, had never heard of the Four Great Grotto-Heavens.
"Master, are the other three Great