The Protoss tribes blamed each other for this and the entire planet descended in a civil war, an age known as the Aeon of Strife. The Protoss worshipped the Xel'Naga as gods, but the Xel'Naga believed their experiment was a failure and left Aiur. Eons ago, an alien race called the Xel'Naga came to the world of Aiur where a species called the Protoss lived and genetically augmented them, believing the Protoss possessed 'purity of form' needed for their experiments.
