He was not certain at all and would question these speculations if they didn’t come from his reliable loved ones.
The world wasn’t aware of how long an epoch was, same with weaker emperors. This was a privilege left to the twelve-will existences that could gaze through the river of time. They came to find that no epoch could escape from this cycle.
Thus, they started the expeditions in order to jump out of this rule so that they could protect their epoch.
Outside of this path, rumor has it that there was a world outside of the destruction cycle, not under the gaze of the high heaven.
It was an incalculable and unreachable world. No one knew how it was formed or what was there, hence the name - The World That Does Not Exist or Nonexistent World.
Of course, the twelve-will emperors could only have a slight idea, unable to actually visit there.
Fei and Deep South were certainly at the very top of the ladder in the thirteen continents. Their mighty power still wasn’t enough.
“Only lords of the epochs can go there?” The prince was shaken, aware of the immense difficulties.
“The lords can’t forcefully do it when the timing and luck aren’t right.” Li Qiye shook his head while pointing at his chest: “Sufficient power, luck, and a dao heart are essential for this journey.”
He paused for a bit before continuing: “Because of this, very few have made it here, and I don’t think anyone had done it in our epoch. In my opinion, our current dark overlords can’t either unless they were to have a breakthrough. But if one of them were able to take this next step, they wouldn’t be hiding in the shadow right now.”
“What kind of world is it? One with immortals?” The prince couldn’t imagine.
“Something similar to ours, not sure about immortals though.” Li Qiye said with a smile.
The prince was very interested in this matter. His father and grandfather were the strongest but they have never seen an immortal. Perhaps this level of being only belonged in the myths.
“That depends on how you define an immortal.” Li Qiye replied.
The prince contemplated for a bit. No one has ever seen one before so he didn’t know how to properly define one either, despite his great knowledge.
“Your Excellency, what is your definition?” The prince looked at Li Qiye.
Li Qiye chuckled and said: “My definition would be, indestructibility and eternal life, without resorting to external items. That’s an immortal. Anything else, regardless of how close, would only be a pseudo-immortal.” 
“Without using external items…” The prince took a deep breath. No one in this world could accomplish this task, at least not in his mind.
Li Qiye couldn’t do it either. His Dark Crow form satisfied the first two requirements but not the third since it needed the Longevity Grass. His current self couldn’t do so either. He hid his souls already but he would still die eventually. There were other powers available that could end him as well.
An “immortal” should be unkillable by anything and have eternal life.
“Then I don’t think one exists.” The prince smiled wryly after hearing this definition.
Li Qiye chuckled: “Indeed, but nothing is certain. Perhaps there are pseudo-immortals outside of our world.”
“Pseudo-immortal…” The prince’s eyes flashed.
“It just depends on the individual’s definition. What’s an immortal in your eyes might only be a pseudo in mine. But either way, our world definitely doesn’t have a pseudo or a real one.” Li Qiye said with a smile.
The prince sighed after hearing this. His father had indeed said that there was no immortal in their world.
“Then you are going to the Nonexistent World because…” The prince deduced.
Li Qiye was amused: “You think I’m looking for the immortals? Well, not exactly wrong because who wouldn’t chase after immortality?”
“You have been in that state before, I was simply curious.” The prince coughed, feeling slightly awkward.
“Perhaps that world really has existences of this level, but like I said, I’m going there to open a new page for this epoch. It would be nice to see these immortals as well.” Li Qiye smiled.
“I simply can’t fathom them at all.” The prince said.
“I don’t know what they are like either, only that there are beings that have survived the ultimate expedition.” Li Qiye continued.
The prince stared at him and commented: “I know that you’re one of them.”
“You are only half right.” Li Qiye shook his head: “In fact, I’m not the only survivor from our own epoch.”
“There are others?!!” The prince was shocked.
“That’s right, even earlier than me in our epoch.” Li Qiye revealed.
The prince took a deep breath after getting this confirmation. His father had told him of this before: “The legend is true then.”
Fei and Deep South have speculated of this possibility before but they didn’t have any concrete detail.
“How did they return?” The prince asked.
“I don’t know. Personally, the final battle is probably impossible to come back from but some have made it in our epoch. There are too many questions about the first expedition, about the participants. Perhaps they were only cannon-fodders for a test.” Li Qiye said with a cold smile and a profound glare.
The prince started to think about the mysterious first expedition. Logically, no one should be able to return alive from one outside of an undying being like Li Qiye. Perhaps all of the survivors were from this period.
He eventually sighed and said: “The final battle, that’s probably even harder.”
The prince was filled with disappointment. The top beings from all the epochs couldn’t come back, including his father and grandfather. He knew them well enough to know that they weren’t the type to give up halfway as deserters. Thus, their fate could be easily guessed.
“Well, I can’t say either, but I believe there is one survivor from the final battle.” Li Qiye said.
“Does that mean this person won?!” The prince suddenly became excited. This gave him hope for his family members.
1. A direct translation would be fake/false immortal; but it doesn't sound right. These beings will still be at the very top of the food chain. Imagine seeing one for the first time and a spectator yells out: “Oh no, a fake-immortal! Everyone run!” - not as impressive and contextually inaccurate. The usage in this case sounds like a title/realm. Pseudo is better contextually, but not literally. It’s tough picking the right one unless the author gives a definition, or tell us that it is a realm. Usually, in many other novels, this is indeed a realm, so I’m going with pseudo. Just note that this would be a bad usage, if someone were to say: “Hah, you’re just a pseudo-immortal”. In that case, false/fake immortal would work a bit better. In Chinese, this title works just fine as a realm and is tone/attitude dependent to show respect or dedain
“The nonexistent world is a thing?” The prince had heard his seniors talked about it too many times: “The reincarnation of the epochs means destruction, but that world is still an exceptional, capable of escaping from all punishments.”