Nearly 800 years ago on a bright day in a land whose name has been lost to time, a young prince rode through the rolling hills of his fathers realm. His kingdom was prosperous and his family beloved by the people. One day he would be king, but today he rode simply to enjoy the warmth of the sun and the freshness of the air. He rode northward towards a line of hills. He intended to climb to the tallest and survey his kingdom in all its springtime glory. Cresting the hill, he turned back to the south to admire the beauty of the lands that would one day be his. The wonder that he sought was there to be seen, but something drew his attention skyward. The sun was high in the sky. It was near to noon. Low on the horizon there appeared to be a bright light rising skyward. For a moment he had the impression that a second sun was rising in the south, but he quickly dismissed that thought as this object was climbing above the southern mountain ranges with an unnatural speed. As it grew larger in the sky he began to detect a sound not unlike the roar of the surf in stormy seas. His fascination was soon replaced with the horrifying realization that this object was not rising, but streaking across the sky, and in fact, falling to earth. There was little time to take in the full scale of the thing. His horse panicked and he fell to the ground as the terrified animal bolted away. Rolling to his back and looking up he could only cover his eyes as the massive light filled the sky. He threw his hands up as if to ward away the thing before it could strike him. Squeezing his eyes tight to block out the sight he was left with only the roar of the thing as it continued to fall. The sound was impossibly loud.
Only the dragonborn know how this object came to be hurled down from the sky to smash into an unsuspecting planet. The great impact is simply referred to as The Breaking by those who have reason to describe it. A vast area of the southern hemisphere was ripped away by the force of the collision. Strangely, much of the remaining areas remained livable. Perhaps it was the will of one of the old gods that preserved the lives of so many. Whatever the reason there were many survivors.
It may have been that the lucky ones perished in the collision. Within a few months the great floating cities of the dragonborn armies arrived to dominate the remaining people.