In the past the planet had a frenetic and savage ecology, which ultimately resulted in the Idirans. By the Idiran-Culture War the ecology had long been tamed and the surviving descendants of the Idirans' evolutionary competitors relegated to zoos. The planet had high radiation levels.
Toward the end of the Idiran-Culture War, the Culture attacked Idir simply by effectorizing its non-sentient computer network. Its designed-in limitations were removed and the computer upgraded itself into a Mind-equivalent.