The Ancients

While there are no humans in this world, there are some artifacts left that seem to suggest an equally intelligent race as Dragons must have lived with them in the far past. What is left from the ones called as Ancients is but a few rusty items made from various metals using technology yet unharnessed by dragonkind. Those few artifacts are oftentimes a closely guarded secret or treasures of unmeasurable value.
It is said that the Ancients will one day return and either bring about the salvation or ultimate destruction. Sources seem to contradict each other here.