There are two methods of introducing races into long running settings.

The Far Reaches route is to pretend like they were always present, they simply weren’t mentioned because the world is so vast that they happened to never be relevant in prior stories.

The Crix War method, now established in the novel ‘Crix War: The Unabashed Storm’ is to properly introduce them as a new force in-setting.

Technically both methods were found in The Far Reaches because when the not-D’Sev were brought in, they were introduced as an enemy that was conquered over the course of three novels.

Regardless, The Unabashed Storm novel sees the planet Crix, currently fought over by five rival powers, suddenly beset by an army of the horned humanoids, the zwelig, named after the ‘zweihorn’, which is a translation of ‘two horn’ which is slang for the zatadun. In a brutal five-year campaign their forces conquer nearly half the planet, before the chaotic Slofrani, based on the Slavani, invade as well and undo much of their progress. The preestablished powers unite to break the backs of these new invaders, and the coalition breaks down the moment the threat is gone, ending with distinct spheres of influence on the planet. Then it’s back to throwing lives away in pointless assaults for scraps of territory.

This summary isn’t a spoiler for the novel. In typical Crix War fashion, this base series of events is carefully explained through maps in the front of the book, which the reader is expected to flip back to for reference. The story and tension, as usual, comes from worrying about which beloved character will be ruthlessly murdered next.

Despite being a continuation of the setting, the novel is fully independent and doesn’t require past reading.