In the 21st century, a meteor hit somewhere. Nobody knows where, but it hardly matters anymore. What does matter is, food supplies fell short, a war broke out, and all the governments fell apart, one by one. It is now a thousand years after that. The dust kicked up by the meteor interfered with communications, and the governments all destroyed each others' sattelites. If any are left, they don't work. The good news is, no nuclear weapons were used for fear of food contamination. Small farming communities lost touch completely, and survive on their own.