Enter the Dragonriders
The Dragon Empire was founded on an Continent on the middle of a Sea between the other continents. It was originally inhabited by other races but the dragons ran out or destroyed all of the evil races that used to rule that land. After the dragons took the continent it changed. Volcanic mountains rose, the seas became rough with jagged rocks and peaks sticking out from the waves,and a mist hung around the seas that made it almost impossible to cross by ship. A chasm opened near the center of the continent and the former cities of evil became ruins.
The dragons make their cities mainly in the volcanic mountains although there are some small settlements suited for the individual dragon types natural habitats.