On the use of articles preceding country names: A pondering

The other day I left the following comment on a friend's blog:

Drew.
You are no longer in the Ukraine.
Write something.
Love,
Jen

This morning, for some reason, I wondered to myself, "Why do we called it 'the Ukraine'? We certainly don't say 'the France,' whereas 'the United States' makes sense because it is referring to an actual group of states rather than simply a proper name. Hm... did Drew say 'the Ukraine?'"

And then I checked, and I see that he did not. And then I became concerned and did what I usually do in instances such as this: I googled it. And to my relief I found at least some sort of explanation.

I found it highly amusing that they used "La France" as an example of countries preceded by an article when this was precisely the country I thought of to refute the notion of using articles before a country's name.

I am slightly relieved that I did not randomly feel the need to place an article before Ukraine, but I still do not understand why it ever began with "the" to begin with. "La Republica Argentina" seems to make some sense assuming this means "The Argentine Republic" (again, a republic being a thing that would require an article). But why is it "La France"? Why?