Warning: This page contains spoilers for multiple campaigns.
The Summer Blight is an event that happened 75 years before the start of the Mheldit campaign, or 146 years before the start of the Erilán campaign. It was a world wide event, affecting multiple regions.
The Summer Blight caused Mheldit's residents to be forced to evacuate the island. A small population of surveyors remained in Port Valiant in order to monitor the situation and assess when it would be reasonable for people to return. It took around 50 years for this to happen and throughout this time, they survived entirely on imported supplies.
It is thought that dwarves also remained on the island, in their mountain strongholds but this is only rumoured, with no concrete proof.
The repopulation of Mheldit caused a lot of unrest, with clashes between the original residents and those who arrived there for the first time. This unrest is far more prominent in the south, particularly around Madail.
Even 25 years after the repopulation of the island, there is still a lot of looting of pre-blight ruins in order to find seeds of crops that existed before the blight.