Sima Nan did not leave. After finding the statue of Bai Xiaochun, which he understood to be God, he chose to stay behind and stand guard over it. In fact, he went so far as to officially declare that location hallowed ground within the starry sky.
He soon found that there were mysterious properties to the area that aided his cultivation. Time seemed to flow differently there. These facts prompted Sima Nan to excitedly kowtow in worship to the statue.
As years passed in which he worshipped Bai Xiaochun and stood guard, he became a much calmer and more peaceful person. However, whenever he looked at the statue, his eyes would burn with unmatchable fervor.
And thus, time passed. Eventually, another archaean appeared from within the 1,080,000 worlds, and then a third, and a fourth....
Archaeans began to appear from within all of the peoples that inhabited the starry sky. Although not every archaean would choose to journey through the starry sky, many did.