Consider Phlebas (Culture, #1)

by Iain M. Banks

“So what happened? It’s a Planet of the Dead; did the natives eventually do it to themselves?” “With biological weapons, not nukes, to the last humanoid, eleven thousand years ago.”

experience as well as common sense indicated that the most reliable method of avoiding self-extinction was not to equip oneself with the means to accomplish it in the first place.

Horza knew the Idirans would never subdue all the less-developed civilizations in the galaxy; their dreamed-of day of judgment would never come. But the very certainty of that ultimate defeat made the Idirans safe, made them normal, made them part of the general life of the galaxy; just one more species, which would grow and expand and then, finding the plateau phase all non-suicidal species eventually arrived at, settle down.