Penglai Fairy Island is located on the back of the Nine Provinces continent, surrounded by sea, it is a rare stronghold of the human race among the Four Seas.
The days and nights on the backside of the Nine Provinces continent are reversed as when it's day on the front side, it's night on the back.
Jiang Li always thinks of the geocentric theory from his previous life when he hears this fact, the theory that states their planet is the center of the universe and the sun orbits around them.
This was later proven false.
But in the world of Nine Provinces, the geocentric theory is correct.
The stars honor the sun and the moon, while the sun and moon respect the Nine Provinces continent. The celestial bodies orbit the Nine Provinces continent, which is undeniably the center of the universe.