Religious event
As Eden grew, they needed a leader for their large city. They appointed Priestess Mary as the leader. She leads with a strict vigour and highly religious ideals. These ideals that the city flourished with.
Eden rapidly began growing, but the people were disorganized. Without a steady government, Eden reached a stalemate in progression. That is, until High Priestess Mary came into the public eye. Denizens came to favor Priestess Margret exponentially, soon electing her leader of Eden in a democratic voting process. The likes of which were later abandoned by the Priestess, making her the only true leader of the city henceforth.