There were once two twin worlds, yin and yang, Female and male.  The world of Yin was covered in life, and the world of Yang was a wasteland, with only sparse vegetation.  Yin was nurturing, while Yang gave strength.  The two worlds were connected to each other by several naturally occurring portals.  This weakened the barriers around them, allowing other worlds to "bleed into" them, creating temporary connections to these other worlds.  These portals disrupted the flow of energy on both worlds, making magic erratic.

The Zyli, beings which could direct the flow of energy and used this ability to travel between worlds, came to these twin worlds.  They felt the energy of this world and knew that as long as the barriers around these worlds were weak, the magic would never stabilize.  Two groups formed, one in favor of reinforcing the barrier, the other believing that they could fix the flow of energy within the worlds with their abilities.  

Without enough strength to reinforce the barrier on both worlds, the first group went the sister world, and the second group went to the brother world.  After several days, the portals between the worlds were destroyed.  A few days later, the Zyli from the sister world created a portal to the brother world.  They had succeeded in reinforcing the barrier.  They created a web of energy across the planet, concentrating the world's energy.  Unfortunately, that meant that outside of these lines, the energy would be extremely weak.

On the Sister world the yang grew, as one cannot exist without the other, and the planet became a more harsh environment.  On the Brother planet Yin grew, and life began to spread.  Soon life from the various worlds it was connected to temporarily began to seed itself across the surface.

The Zyli from the Sister world knew that they had weakened themselves when they severed the worlds from each other, so they built cities, intent on teaching the various races on both worlds of magic, in a attempt to prevent magic from dieing on either.  They became known by the other races as the First Ones.

On the world of Yin, humans slowly became the dominant lifeform and, with portals to other worlds usually being artificial and rare, they managed to become the dominant lifeform, using technology instead of magic.  On the world of Yang the many races competed and struggled for survival, and learned to cope with the constant influx of new people and creatures.  Their magic grew in strength and complexity, despite the sparse and erratic nature of the world's magic.

The world of Yin became known as Earth, and the World of Yang became known as Mym.

-The Twin Worlds, First ones mythology

[hr]

Siana closed the book and placed it back on the library shelf.  She couldn't remember reading that story before, but it seemed familiar, as so many things do.  A local warriors guild had loaned her the use of their facilities for meeting her new team before they left for the mission, the one in which she would lead them into the Fog.  She knew they thought she was going to die, as few of them would even brave the Fog, but for whatever reason, she was confident she would find the town by the lake.

As they entered, she watched them.  They had met before to get an idea of the abilities of the others, but knew little about each other besides that.  Hopefully they would learn more about each other on the journey.  "Thank you for coming." she said to those that showed up, noticing that several would had shown up at the original meetings had not shown up to head into the Fog.  She couldn't really blame them, though.  "If everyone is here, then we'll leave.  It will take us about a third of an hour to get to the point where we must enter the Fog."