Earth

Earth is a location that is mentioned in the Sonic the Hedgehog book series. It is a planet far away from Mobius, and is where most humans reside. It heavily resembles Mobius of days past when it was also called Earth, but has different land formations. It is said in Sonic's Hourglass that Sonic and his friends often travel to Earth on their many adventures.

History
A long time ago, two beings were created to eternally fight over the newly created Earth. These beings were Light Gaia, and Dark Gaia.