Explain Like I'm 5 (ELI5)

We also see this line between the "Eastern" and "Western" worlds set along the border between Europe and Asia, which adds this centuries-long enforced cultural separation, if not a geographic one.

Not that it's an exact parallel, but it's also like how there exists this need to define the geographic space of "Latin America" as this distinct environment. Despite sharing a massive land border, the US and Mexico likewise have this culturally-enforced separation that is used to demarcate these regions more often in discourse than simply "North America" and "South America".

And there are some cultures that consider the Americas to be a single continent, too.