War of the Wyrms
The peoples of Quartos started their own civilizations. Tiamat wished to conquer the developing nations and claim the continent as her domain. Bahamut desired to protect the peoples and let them determine their own fates.
Dragon clashed with dragon. The Metallic Dragons were victorious, but Bahamut could not destroy his sister so quickly after they had defeated their father Yg. Instead he exiled her and her kind from Quartos, founding the first order of paladins to ensure that any dragons outside of Bahamut’s followers were slain.
The Quartosian calendar moves forward from the date of the war. It has been 690 years since Tiamat’s exile.