Alright, random concept:
At one point, there was a villain who was trying to bring back the dinosaurs. He thought the best way to do this would be to make Pangaea again. So he did. It didn't succeed in bringing back the dinosaurs though.
After that, there was a bunch of political problems, like "well where the hell are we supposed to put our borders now!?" and "How are we supposed to rebuild all our civilisations since the earthquakes from moving the continents destroyed them all!?" so in the end, a Big Council of People was created, and it identified all the good places to build cities in. Those places were then distributed amongst the countries according to their remaining population and state of technological advancement.