The long War Rising
Dragons are the primary viewed as the most direct connection to the dead gods. During the War of the Gods the gods created dragons to be the frontline warriors for them. After the war ended the only dragons that were left small hatchlings, as such there are no living dragons that have memory of the war.
With the gods widely considered to long dead and gone, the dragons are considered to be the caretakers of the realms that the gods left behind.