Fifth Umbral Calamity
The Fifth Umbral Calamity, also known as the Calamity of Ice, heralded the end of the Fourth Astral Era and the beginning of the Fifth Umbral Era, or the Age of Eternal Frost. Tribal legend and local folklore speak of a seemingly endless winter that brought with it bitter cold, raging snowstorms and giant rivers of ice. Without the ability to grow crops much of the population either perished, or were forced to flee to the south and it's more temperate climates. It is believed that for most of the era much of the Bloodbrine Sea was frozen solid, one one hand preventing fishing and decimating the populations of sea life, but on the other, allowing for the migration of Miqo'te Tribes from Southern Ilsabard into Northern Eorzea. The frozen seas allowed them to circumvent the massive peaks of Gyr Abania that had kept them from returning to the lands they had been driven out of almost two millennia earlier by the Allagan Empire.