"The San'Zeran system is defined by dualities. There are two suns, two moons, two continents, two peoples, two eyes in each of our skulls, two hearts in each of our chests."— An unnamed philosopher
Just over a thousand years ago was Darkness. During this time, Sanoris and Auzera did not interact with each other. The civilizations on each continent stubbornly fended for themselves in a world where the strong dominated and the weak were forgotten.
Eventually, the Darkness ended. It is not known what triggered its retreat, but over time there was healing. The two continents began to interact again. They met together in a great convention and created a new era. An era of community, trade, and prosperity.
Whatever happened before the Dark has been lost forever. The only thing that remains are hundreds of ruined cities--empty husks that teeter next to large bodies of water. As the years have waned on, the cursed cities have continued to crumble, and with them any memory of what created the Dark in the first place.
But things are stirring. A beast awakens, somewhere unseen. There is something in the water, and it hasn't yet finished its work.