The Dragonflight was the exodus of dragon, human, elven, and dwarven armies from the island of Obadon which occurred in 4546 AV.
The dragons took their subjugated people, had them built a massive fleet to carry their armies across the vast Altric Ocean, intent on reclaiming their lands that was lost to Azmodeus and his demon legion in the Old Kingdoms.
The day came when the dragons emerged from the skins of the gnomes. They revealed their millennium long plan to gather the forces of Obadon and sail back to the Old Kingdoms and reclaim what was once theirs. Dragons living to be thousands of years old still remembered their homelands, the mortals they tried to convince, not so much. It took decades for the dragons to raise an army large enough to battle the devil god and his demon armies. Once the mortals were convinced, either through force or charm, the dragon armies sailed to the Old Kingdoms leaving behind the too young to fight, the too old to fight, and the too sickly to fight.
It has been over a century since the Dragons Armies took flight across the ocean. They have not been heard from since. Many people speculate they succeeded in regaining their Old Kingdoms. Other say they drowned on the way victims of the gods of the sea. Yet others believe they quickly died at the fiery hands of Azmodeus and his army. Whether they won the war, found another continent to call theirs, or if they simply vanished, none know for certain.