Kali Yuga
Indian word for an age when human civilization descends into absolute degeneracy. For starters just imagine it as a post-apocalyptic Mad Max-esque world.

Hindus believe that at the end of this dark age, Lord Kalki will come to punish and cleanse the world, which would have devolved to the point of being incapable of enlightenment. Coincidentally, Ra's al Ghul also wants to do the exact same thing but then he has to worry about Batman getting in his way.
Blue guy : Borders are stupid, we should totally have open borders and let everyone into America.
Red guy: If we open the floodgates for them degenerates then it's a one way ticket to Kali Yuga.