The Great Expansion is the first age of the Modern Era, spanning 9,950–0 BSD. Not everyone perished in the Shattering, and those who survived began the work of rebuilding.
Frost Fall: 8,840–8,695 BSD
A 145-year period of severe cold that tested the early recovery of civilization. The water plane Pelus had drifted close against the material world and held there, and the cold bled through until it withdrew. Its course and lasting mark are covered in the Frost Fall's own entry.
The Return of Dragons: 8,104 BSD
Most sentient creatures did not get along with dragons, who were quickly taking over. This led to a great deal of fiery and bloody conflict as the rebuilt peoples of Alaria struggled to coexist with the dragons returning to prominence. Where the returnees came from, and why their re-emergence turned so bloody, has its own account in the Return of Dragons.
The World Fire: 10 BSD
The age ended when a fire-paragon over-channeled the Yolus seam until it ruptured, the cataclysm that gives the World Fire its name. The surviving calendars fixed their zero in its aftermath, the boundary between the BSD and SD reckonings. Its course and lasting scar are covered in the World Fire's own entry.