The wold was destroyed when the sun flares hit. Some of the major cities were saved for the people who were still healthy. Eventually even the most protected cities fell to the cranks who either drove all the healthy people to the wilderness or ate them.
ch: draco malfoy // dragons are very honorable. we will not betray our own. you are one of us now. we will teach you our ways. and if you betray us we will not kill you, the opposite in fact. we will keep you alive forever in agony