It is rumored that the Precursors created both the Forerunners and the Humans. They were put at relatively opposite areas of the galaxy. The Forerunners and the Humans both advanced at relatively the same pace but the Forerunners were arrogant. They overturned the Precursors. The Humans learned that their Precursor "wardens" were in a conflict and losing. The humans then captured a precursor and rose up. The defeated and ashamed Precursors then fled to an unknown fate. The humans and Forerunners then led separate but relativaly equal societies until human-flood war.