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

The old man was rather calm. His expression was cool as he glanced at Sun Wanshi and said indifferently, "Are you sure that it's really the Deva who infiltrated the Upper World with the help of the Heavenly Cycle Star Pavilion?"

"There's no doubt about it." Sun Wanshi nodded solemnly and said, "That Song Zhong has the power of a Deva Dharma Idol, and there are only a few Devas in the entire Great Zhou.

"The Heavenly Cycle Star Pavilion has already announced that they are going into seclusion and will not come out. It's impossible for the Black Yellow Heavenly Palace to help these families. Pei Qingshu and Li Mingqiong are also not here. Other than the Deva from the Lower World who infiltrated the Heavenly Void World, who else can it be?"

"What if it's that Peerless Sky Demon from the Lower World?" the old man said bluntly. "What if this is just a bait to lure us over?"

Nine Elders of the Immortal Sects