Ry,
You're giving me an idea for an AW game, where some serious large-scale nuclear disaster (maybe like Chernobyl, maybe as the result of a way) leaves an area of the globe destroyed, scarred, twisted. The earth is barren, except where mutated and bizarre, powerful new lifeforms grow at alarming rates.
That's where the people of Apocalypse World live.
But the rest of the world? They've built a huge fence around this prohibited area, and are going on living their lives. No one and no thing is allowed to leave, of course, so there's not communication between the two worlds.
In some parts of Apocalypse World (a sort of natural reserve, or native reservation, one that nobody ever wants to visit), you can see the clouds of acrid smoke produced by the distant and unreachable Great Cities, billowing for hundreds of miles into the reserve.