Story of the three races and the emergence of the six characters
The Celestial Monarch and Ten Veiled King created humans to cultivate the lands of the Immaculate Lady of Earth, taking pains to protect this race against the warping effect of the Yang and the sterilizing effect of the Yin. These humans, new and pleasing to gods and demons alike, rapidly multiplied and their number covered the Land of Pangu and after thousands of years, both the Celestial Monarch and the Ten Veiled King had finally deemed decided to return to their respective dominions. Both august sovereigns sealed of all portals to the Heavens and the Underworlds, leaving behind a handful of powerful gods and demons to oversee the development of the Land.
Then one night, a burning brightness followed by a numbing darkness suffused the realm of Pangu that caused all the gods and demons to vanish. In the wake of their disappearance, three new cities were discovered: Feather City (where winged humanoids dwell created by the Gods), Beast City (where beast like humanoids dwell created by the Demons) and Dragon City (where there only remained two infants – one boy and one girl).
Soon, relationships between cities and races became strained and the inhabitants began to wage war with each other. Kingdoms built by warlords and tyrants rose and fell, borders shifted yearly, and the scent of blood and the ring of combat was commonplace throughout the lands.
From Perfect World Wiki