Everlight is a tropical island used as a retreat by the elves. The Empire has recently captured much of Everlight. The Fourth Overlord journeys here to recapture the green minions and capture the town. The Elves go there, when they are sick and tired of the earth. There is a rumor the elves go to Everlight to meditate and spiritually be with one in the universe. The Glorious Empire used it as resort for the wealthy citizens and area with many captive magical creatures.
Because of Evernight being turned into the wasteland they fled to the island of Everlight they most probably left when they saw small problems with their habitat, such as mutated animals and to avoid gaining contact with the magical plague.