Outside the valley were the stands; inside, the Arena.
The valley was where the Godlight Shard would soon appear, so the Divine Children arranged their forces here, letting their Divine Descendants fight and slaughter each other on the spot.
As for how the fight started, it was quite simple—where there were people, there was the Martial World.
Ren Suo observed their reasons for fighting, which ranged from "What are you looking at?" "Looking at you, what about it?" types of trouble-seeking; "XXX, you didn't invite me when you went out to play ten years ago, I remember it; come down and die!" types of grudges; and "You're so ugly; just stretch out your face, and turning it into a mash might make it look better" types of discrimination.
