Aiur

From Multiversal Omnipedia

Aiur was the homeworld of the Protoss. It was invaded and conquered by the Zerg, but Protoss counter-attacks, most significantly those of Tassadar, led to the destruction of the Overmind after it settled on the planet. However, without direction, the Zerg broods scoured the planet, forcing the remaining Protoss to evacuate to Shakuras.