300 million years ago, Earth didn't have 7 continents but istead one supercontinent called "Pangea". 200 milllion years ago it started to break up and formed 7 continents over the time. At some point of our history, people came up with the intangible idea of borders. As the borders restrained people from moving to other parts of the world, segregations escalated. We should remind ourselves that nature knows no bordrs and we all come from one land, which is Pangea and hence the world is ours.