The Autumn Felling is a legend that speaks of a day when over half the elves in Alharth suddenly dropped dead.
The Gods, XI: Arisetsu
“History of Arisetsu (Council Annotated Edition) The Fennyra Crystal, the treasured memories of a million long-dead elves, shows a time unlike ours. In the age when humans and orcs were simple primitives, elves were more magical, more in tune with other realms, and their lifespans much longer. Although some sang songs of worship to Cae-a-lee, most elves cared little about gods, so the other elven gods were small. The Crystal's last memory ends with the Autumn Felling, when half of all elves died and the rest were left in agony and despair. Cae-a-lee died too, right when elves needed her most. As elven lands rapidly fell to other races, two minor gods came to their rescue. Ir-Hetsu, god of Wind, and his sister Aris, god of Warmth, guarded the last million living elves in the city now called Arisolme.