When Meng Xiaoyao ended his cultivation in seclusion, he could go to any location on Earth freely, including the Twelve Divine Gods and Demons Array created by the Great Ancient immortals, as well as the magical and unpredictable Ten Thousand Demon Realm, and the Eye of the Sky Demon which existence was not yet known as it could not open on its own back then.

He learned that the three sites were actually three worlds linked together!

The Great Ancient immortals used their magnificent imagination and unpredictable powers to create that masterpiece. 

There were only a handful of powerful Great Ancient demons with overly great Yin energy being imprisoned in the array, but they put a huge burden on the illusionary dimension.

Thus, the Great Ancient immortals used the unique space in the Eye of the Sky Demon to link with the array and go about absorbing the Yin energy within it. 

Coincidentally, the Yin energy could be coalesced and then formed into Zi Qing Heavenly Lightning, which was a kind of Yin lightning. Having been injected into the top of the Sky Tower, it was used to suppress the demons who wanted to get out of the realm through the tower. 

The Great Ancient immortals had designed all these because, at that time, they had decided to leave Earth.

They were powerful enough to travel freely through the universe and explore more mystical worlds.

Earth was indeed their home for hundreds of thousands of years, but they had their own ambitions. With a wider world in front of them, they could not remain on the planet forever.

Thus, for the sake of human descendants and their home, Earth, the Great Ancient immortals decided to use this method to control the demons and devils and kill and seal some of the unruly, ferocious, demonic beasts, such as Chaos Beast and Taowu, before they left.

Afterward, the Great Ancient immortals recorded the things they did on the top floor of the Sky Tower.

Although it seemed to be a "prison" for demon cultivators, in reality, it was only used by the Great Ancient immortals to separate the human and demon races, to prevent the two sides from carrying out endless slaughtering.

Among the Great Ancient immortals, there were humans, demons, and devils, so they did not know who would be in charge of Earth when they were gone.

As a result, in addition to documenting this history, they also left some "instructions" for future generations at the top of the Sky Tower. The gist was that whoever could brace through the ninety-nine lightning bolts of the Zi Qing Heavenly Lightning and arrive at the top of the tower, whether it was a righteous practitioner from outside or a demon cultivator from the Ten Thousand Demon Realm, it meant that they were strong enough and we weren't just some lowly cultivator.

In fact, Yang Chen was the only "special case" that was overwhelmingly powerful. First, his body was ridiculously strong from undergoing various transformations. Secondly, he had an immortal weapon like the Chaos Cauldron in his hand. If one were to speculate based on the Great Ancient immortals' capabilities, those who could arrive at the top of the tower by their own strength would basically be close to becoming one of them, as in the case of Yu Xuening.

Those who reach the top of the tower can make a choice. The first one was to take away the Nao Drum, release the demons in the Ten Thousand Demons Realm and let the clans fend for themselves. The second one was to leave the Nao Drum behind and continue to keep the human clan separated from the demons and devils.

It was tantamount to giving equal opportunities to the human cultivators as well as demon and devil cultivators. If an expert powerful enough to crush the human race emerged among the demon and devil cultivators, then it was the fate of the human race.

At the same time, if the demon cultivators and demon cultivators failed to reach great heights, they could not blame anyone. 

Meng Xiaoyao had entered the Ten Thousand Demon Realm through the Demon Lock Tower due to his curiosity. 

The Sky Tower was open all the time at the time, not only once every 60 years.

After wandering around the Ten Thousand Demon Realm for some time, Meng Xiaoyao went straight from the lower levels of the Sky Tower to the topmost level. His ability at that time made it easy for him to withstand the Zi Qing Heavenly Lightning.

When he found the letter left by the Great Ancient immortals, he realized that he was the first person to discover this secret, because, during that time, no one knew where the immortals had gone to. It had always been a mystery.

It was only through the letter left by the immortals that he learned that Earth had been under attack by alien celestial bodies for hundreds of thousands of years in the past. Moreover, it had always been the immortals who had destroyed some particularly threatening celestial bodies, either by crushing them outright or by knocking them out of their orbits. 

Earth was like a biological mother to them, and naturally, they have special emotions towards it. 

The immortals hoped that those who came after them would continue to guard the planet. After all, they had done so much for it, and it was time for them to leave.

Anyone who had the opportunity to see that message had the ability to do so, not to mention they could also borrow the power of the Nao Drum if they were not strong enough. 

It was expected of the Great Ancient immortals to leave behind words that contain an unparalleled "Dao."

After reading everything, Meng Xiaoyao immediately gained plenty of enlightenment at the higher level, which was equivalent to receiving the "kindness" of the immortals and forming a "bond" with them. 

Meng Xiaoyao knew he would have a guilty conscience forever if he were to stay out of the matter and pretend not to know about the immortals' request and thus would never be able to keep his mind free from distractions.

Therefore, he silently accepted the commission to protect Earth. Even if he could leave the planet long ago, he still stayed on for more than 50,000 years.

However, Meng Xiaoyao also had his own plan. He could not stay on Earth forever and would eventually have to leave and follow in the footsteps of the Great Ancient immortals and go to the vast starry sky.

He, himself, too, needed to find someone who could pass on this mission and help him to end it.

When he first went through the door at the top of the Sky Tower and witnessed the Eye of the Sky Demon afterward, he had a plan in mind.

Meng Xiaoyao took the key to the Eye of Sky Demon, the black ball, and then exited the Ten Thousand Demon Realm from the Sky Tower.

At that time, the war between the righteous cultivators and the demons was in full swing.

With his capabilities, he sneaked into the Xiao clan and became a foreign elder, calling himself "Xiao Yao," but he did not show his true cultivation.

It was at that time that he and Yu Xuening, who was also at the top of the rank, became associated with each other. Unfortunately, he had a mission, so it was impossible for him to be with her. Thus, even though the beautiful woman was interested in him,  he rejected her. 

Although Yu Xuening was intelligent and could guess many things that the others did not know, she resented the truth. Too unbothered to be a stumbling block to Meng Xiaoyao, she entered the  Ten Thousand Demon Realm by herself.

Meng Xiaoyao did not stop Yu Xuening either, for he had more important things to do.

In several major battles, he attracted a large number of enemies, who were also the strongest experts at that time. With that, the great forces fought a great battle at the Eye of the Sky Demon.

At that time, countless devils, demons, and righteous cultivators converged there. Meng Xiaoyao pretended that he was seriously injured and blew himself up, but in reality, he exploded everyone into pieces, causing their souls to plunge into the Eye of the Sky Demon and form countless demonic spirits later on. 

Because of what Meng Xiaoyao did, the Eye of Sky Demon became a special world that opened once every hundred years.

Since he took away the key that connected the Eye of the Sky Demon to the Sky Tower, the gate was closed, resulting in the inability of the Yin energy to enter the Nao Drum smoothly and continuously.

Thus, the Ten Thousand Demon Realm also became a world that opened only once every sixty years at that time.

Meng Xiaoyao left the black ball and "death note" with the Meng clan, which was considered an ending to destiny since he was from the Meng clan. Thus, it was considered a reward for the Meng clan.

While he did give them the black ball, he only said that it had a chance of reviving demon cultivators but did not specify how. That was because he hoped to let fate decide all this.

If the devil demon cultivators one day conquered the illusion dimension, then naturally there would be a chance for the black ball to be used, just like what Yang Chen did at that time. If they did not win against the righteous cultivators, it was destiny and could not be changed.

Another 30,000 years passed, and Meng Xiaoyao had been fulfilling the Great Ancient immortals' wishes, silently watching over his descendants while helping Earth deal with the celestial bodies before they even came close.

However, he found out that he was getting stronger and stronger, and his realm was getting more and more profound, but every younger generation was worse than before.

The devil and demon cultivators hid in the Honghuang realm, not daring to come out...

The righteous cultivators were in the illusionary dimension, doing all sorts of deceitful and nonsense. Although there were good talents occasionally, they were not properly cultivated. 

Eventually, he became confused as to whether there was any need for such a group of descendants to remain on Earth.

Was it really right for humans to be the dominant race on Earth? Was it truly beneficial to allow mankind to avoid demon and devil cultivators?

He had long since transcended these frameworks of ordinary humans, righteous cultivators, demon cultivators, and so on. Thus, he was not on any of their sides. 

Just when he could not find an answer and was at a loss, the Gods descended!