At the end of the A.D. era, the exhaustion of Earth's petroleum resources and worsening environmental pollution brought about a worldwide economic collapse. The world's nations formed economic blocs, dividing the planet into a handful of major powers. Increasing ethnic and religious strife soon led to a third world war, known as the Reconstruction War, in which the world's nations were merged and reorganized. The conflict continued to escalate until nuclear weapons were employed on the frontlines of Central Asia's Kashmir region. The resulting shock motivated the combatants to resolve their conflicts peacefully, and the Reconstruction War eventually came to an end in the year C.E. 9.