It is said that once upon a time two more Dragon species lived, black and white. Nowadays nobody knows for sure, because no one has ever seen one, or at least they don't remember it or didn't live to tell. Not much is known about these two species, it is rumored that the White ones were good Dragons, and the Black ones evil.
Legend says that the White Dragons can be revived by hatching the last egg. This egg however is, obviously, hard to find. The legend foretells that whoever hatches the egg, the White Dragon will be loyal to that person, no matter who that would be. This egg is supposedly divided into six parts, locations.
Other rumors say there is even a second egg, hidden better even. Protected by an ancient order, devoted to the egg.
The Black ones are a bit harder to find, but there are more rumors about them. Stories are being told of Black Dragons jumping out of the shadows and taking people. This means that they supposedly aren't extinct. In ancient tomes stories tell of several eggs still intact, scattered around the continent. These eggs could be found in "the darkest of places".