Pangea

According to the most widely-accepted current theory (as I understand it -- and I don't claim that I do), all the current land on earth was once part of a single continent, called Pangea.

Pangea started breaking up about two hundred million years ago, and the various pieces have used the ensuing time to move to where they are now (and they continue to move, I am told, though I must state that I've not seen any of them do so).

I've seen maps of Pangea before, but I enjoy this one, which shows where today's countries were way back when.