In the late Middle Ages some scholars argued that there could not be humans in the southern hemisphere... a.k.a. antipodes

The idea was that it gets hotter and hotter as you go further south. Eventually it would get too hot for people to survive, certainly at the equator. So you can't cross to the temperate parts of the southern hemisphere.

The Bible doesn't mention creating any other people on the other side of the planet, and none can get there from the northern hemisphere, so therefore they must not exist. Q.E.D.