The origin of the The Warriors of the Magus is told as legend:

"For eons, the Sorca say, the Keeper ruled the land caring for it herself until the birth of her children.  Twins they were - one male, one female.  Two halves of a whole but different as night and day.  As siblings can sometimes be, they were very competitive.   When the Keeper judged her children ready, she ceded the earth to them dividing it equally.  The North she gave to her daughter, her first born, and the South to her son. 

Instead of living with their mother's vision, the twins changed their hemispheres to suit their own personalities seeking to improve on the Keeper's perfection.  Such ambition, even for a one born of a goddess, was disrespectful and of course impossible.  With each alteration, each addition, each enhancement to their domains the siblings grew jealous of one another.   In time rivalry built to enmity and finally open violence as they warred with each other covering the world in a conflict that threatened to destroy all the goddess had labored to create.

In the end, the Keeper intervened banishing her children from the world as punishment.   But, she did not heal their changes or the effects of their war and ever after the differences remained between the two halves of the world - between the Verga and the Rimlands"