They have these nomad madmax thunderdome like dudes who harass and try and steal their resources and cause conflict. It's pretty well done in terms of realism if the an event did occur. Obviously you have to watch it in that state of mind, knowing in the back of your head it's not actually real. So far though I've only seen the 2nd episode, will be interesting to see how it pans out and how well the survivors do.
