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

"Origin Great Daos that manifests as the Point of Origin of different universes are usually different, but there's also a point that must be the same. That is, there must be an Origin Great Dao that represents 'matter' that is limited to the origin. This might be the Origin of Five Elements, the Origin of Four Symbols (Azure Dragon, White Tiger, Vermilion Bird, Black Tortoise), the Origin of Particles, the Origin of Stars, and so on. Their essence symbolizes an existence on the material level of the universe.

As long as we destroy this Origin Great Dao's Point of Origin, it will collapse, and the entire universe will collapse on the physical level.

And matter is the foundation of all existence in the world. The Great Dao, laws, time, space, and so on have to be reflected by matter. Once matter collapses, everything will collapse.

In this way, the entire universe will fall into an unstoppable destruction. It will first turn into nothingness and return to chaos."

Legacy of the Supreme God of Heaven, The End of the Path to the Return to Void Realm (3)