Zone 30.

In AD 535-536, humankind was hit by one of the greatest natural disasters ever to occur. It blotted out much of the light and heat of the sun for 18 months and the climate of the entire planet began to spin out of control.

The explosion tore through the same South Pacific region that later gave rise to the Krakatoa eruption in 1883. The earlier convulsive detonation created the islands of Sumatra and Java and left behind a gap that is now known as the Sunda Straits.

The eruption's aftermath was felt worldwide. "Crops failed in Asia and the Middle East as global weather patterns radically altered. Bubonic plague, exploding out of Africa as the climate change increased rodent populations, wiped out entire populations in Europe. Flood and drought brought ancient cultures to the brink of collapse."
Earth Island Institute