Sole Cloud Flying Cave

Cui Heng was transmigrated to another world and the system told him that the new world he was in was a high-grade Xianxia world.
It was a world where Celestial Kings soared the sky and terrifying monsters ruled the lands. The strong would destroy a planet if their mood was bad and Cui Heng trembled in fear when he learned of how scary the new world was.
Thankfully, the system had granted him the protection that last for 300 years. As long as he remained in the safety zone, he would not receive any damage.
With his safety secured, he began his cultivation training for the next 300 years.
Throughout the years as he trained, some people entered his safety zone by mistake.
There was a peasant who was once a monk and a beggar. Despite that, he still had the dream of bringing peace to the land and saving the lives of millions.
There was a noble who was once called the once-in-a-million-year genius. Yet, luck wasn't at his side and his talent fell and was laughed at by others for years.
There was a princess whose only wish was to find her older brother. She could've become a celestial but decided to remain in the human realm to wait for her brother's return.
There was a weak lady who was plagued with illness from birth but had the goal of adventuring and helping the poor and weak.
...
Cui Heng befriended these people and even gave them a few pointers before they left.
300 years later, when the protection period had ended, he had finally mastered the Golden Core. Even then, he was still reluctant to go to the outside world.
But when he did, he realized that the world was merely a world of Wuxia.

Realizing This Is A Wuxia World After Cultivating For 300 Years

Before he could finish his sentence, the atmosphere in the sky surged violently, splitting open a path in the middle.

The end of this path flickered with golden light, as if it contained another world. It was filled with a vast and ancient aura, as if an existence that had lived for countless years lived inside.

Then, a figure walked out of the golden light. The golden light behind him retracted, and the sky returned to its previous state.

This was an old man who looked to be in his sixties or seventies. His hair and beard were white, and his eyes were kind. He was wearing a white robe, and his body emitted the aura of all techniques fusing into one.

It was the Myriad Techniques Return to One Realm, but he was far stronger than ordinary Sages.

He should be a so-called Sage King or a Great Divine Being or Star Lord.

It was equivalent to the Peak of the Sixth Realm of the Immortal World.

Chongyang Star God, Realm Breakthrough