Era beginning/end
The end of the Third Age and the beginning of the Fourth Age.
This era was occupied mostly with the Cold Plague, and the recouperation afterwards. Towards the end of the age, some folk began getting antsy with the way things were, and where they were. With the destruction that the plague brought, people began to shift and move around from where they had been for many years. That brought on the fifth age; the Age of Exploration.