Probably results of varied trade deals, buisnesses, colonization, and just a long history of how the world has globalized in general.

Region 5 looks like they said “screw it, let’s just throw all the countries left into a single region and call it a day”

For a second I thought maybe due to their historical colonial ties to the UK but that logic falls apart when you realize AU and NZ are in a separate region from the UK… so… 🤷‍♂️