The Krynn are not a single species but a number of sentient species that developed on their homeworld nearly simultaneously. Unlike most species that have known civil strife, bloodshed, and chaos, the Krynn rallied around a singular vision for the Universe. Being actually a "culture" more so than any single species, it allows any race to be a member of the Krynn (which explains their high espionage skills, the Drengin next to you can actually follow the Krynniac principles). Another core belief of the Krynn is that all living creatures can/have/or will be a Krynn, and so it is important to save everyone's "soul".
The Krynn are in some ways fundamentalists, and also, though having some strong diplomatic abilities, take a different approach than Humans. In that Humans look to make allies, the Krynn use their abilities to bring more people into the Krynn.
The Korath Clan was a part of the Drengin civilization. Following the First Galactic War where the Drengin Empire defeated the Terran Alliance and its allies, the Drengin and Korath disagreed on what to do with the conquered peoples they now had in their control. The Drengin wanted to continue in the slavery and subjugation to increase the Drengin Empire's overall power. The Korath wanted nothing more than the total annihilation of all non-Drengin life. The Drengin, knowing that having no underlings would only lead to a weak empire rife with internal struggles, fought against the Korath. Unbeknown to the Drengin, the Korath were actually being used and empowered by the evil Dread Lords.
And now you know a bit more of the story