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

In the palace in the capital of the Wood Nation.

Cui Heng's eyes were slightly closed as he sat cross-legged in the air. His entire body emitted a bright silver light, as if he had the ability to wither and decay everything.

He was comprehending the mysteries of the Time Saber.

In a pavilion not far away, the Princess stood there. She held a plate with both hands with a teacup and teapot on it as she quietly looked at Cui Heng.

She had been arranged by the Wood Emperor to come over.

According to the Wood Emperor, Supreme Venerate Cui's disciples and followers had already left. Letting this esteemed guest live alone in the palace would seem like the Wood Nation was not treating him well.

However, it was clearly not appropriate to let ordinary palace maids serve him.

Hence, after obtaining Cui Heng's agreement, the Wood Emperor sent the Princess, Mu Lingyun, to this palace to serve Cui Heng.

Time Like a Saber, Slaying a Genius