The Red and Blue Fire sect is from the northern region. They used to own one rank 6 secret realm and many rank 5 secret realms. But once they lost the power needed to hold onto what they owned, they had to descend to the lower region.
They had many options to descend to, but the one they picked was the Five Veins Region.
The Five Veins Region that he is at currently descended from one of the grade five secret realms. So that single grade five secret realm had produced five grade four secret realms.
The neighbors of the Five Veins Region on both the east and west are grade four secret realms that are offshoots of the six grade five secret realms above them.
So there were many choices for the Red and Blue Fire sects to invade. If not for the fact that the Purple Flower sect was susceptible to their techniques. The war wouldn't have happened.
