Disaster / Destruction
At the climax of the Dragonsong War, something happened that is still debated to this day, but what we know here in Faerun, is that the island consumed all upon it, it was a maelstrom of chaos. No one went near.
When the Dragonsong War came to its zenith, an explosion felt around the world went off. The land of the Rifts, became shroulded in a swirling vortex of what can only be described as a magic storm. Faerunian soldiers were trapped inside, presumed dead. The dragons never went back to Faerun. And no ships from Faerun could pierce the maelstrom, for none ever returned beyond scouting range. In the waning years of this period, the Drakestorm began to falter, and in 1754 it fell, and the first ships could make beach upon the Rifts shores. Colonization begins immediately.