Question is pretty self-explanatory but it just struck me as odd that so many countries in english have this suffix especially when many of them formed their names at different times. The only thing I noticed was that they seem to be absent from Western Europe. Is there anything behind this?
http://etymonline.com/index.php?term=-ia&allowed_in_frame=0
It denotes an abstract noun of feminine gender in Latin and Greek. So basically, you can take anything and add this suffix (if it's a feminine word in Latin or Greek) to "nounify" it.
The link says Chinese has a similar mechanism. Of course, this is a linguistic answer. If you're looking for a historic reason as to why English uses Latin and Greek influences in "international matters," I'll leave that to others. No idea what source material exists with citations.
This is off-topic but /r/linguistics might be able to give a pretty good answer