So, bear in mind that I have a somewhat limited grasp of Eastern European history.
I know that there are two types of Slavonic languages: Southern Slavonic (the former Yugoslavs, Bulgaria, Macedonia, etc.) and the Western/Eastern Slavonic languages (Czech, Polish, Russian, etc.).
My question is, why is there such a geographical separation between the two? Looking at a map of Europe you'll see that the Slavic tongues are firmly divided by Romania, Hungary and Austria. Why are those three countries so free from the influence of the languages to the north and south?
>>I know that there are two types of Slavonic languages: Southern Slavonic (the former Yugoslavs, Bulgaria, Macedonia, etc.) and the Western/Eastern Slavonic languages (Czech, Polish, Russian, etc.).<<
I would say there are three groups. Besides Southern Slavonic (or Slavic), there is the western group (Polish, Czech, Slovak, along with some minor languages), while Russian, Ukrainian and Belorussian belong to the eastern group. If, however, you meant that the separation occurs between East and West Slavonic languages on the one hand, and South Slavonic ones on the other, then it is right.
Now the answer to your question:
The Slavs gradually populated the area of the Balkan Peninsula from two directions (west and east) from the 6th century A.D., where they found an existing Romanised population which they partly assimilated and partly forced to migrate (there is still a scattered Walachian population in parts of the Balkan peninsula as a proof that a Romanised population used to live there). At that time, the Slavic population of Pannonia (present-day Western Hungary) formed a link between the South Slavs and the rest of the Slavonic tribes. There also existed a cultural link between the two, for example, the ruler of Great Moravia, Prince Rastislav, gave a commission to two clerics in Thessalonike, Cyril and Method, to create a Slavic alphabet.
This link was "disrupted" by the invading Hungarians, who put an end to Great Moravia, and gradually assimilated the Slavic population of Pannonia. The Slavic people that later became the Slovaks (their name simply means "Slavic") lived under Hungarian rule for 1000 years. The same was true for Slovenians (another name meaning "Slavic"), who in turn lived under Austrian rule until the creation of Yugoslavia (formerly called the Serbo-Croato-Slovenian Kingdom) between 1918-1920.
>>Why are those three countries so free from the influence of the languages to the north and south?<<
They are not completely intact from such influence. Hungarian and Romanian have many Slavic loanwords. The German spoken in Austria was not directly influenced by Slavic languages, but you will find many Slavic-sounding surnames there (mostly of Czech origin), like that of the former Austrian chancellor, Franz Wranitzky. The historic Kingdom of Hungary also comprised a large slavic population (from all three groups: Croats, Serbs, Slovaks, Ruthenians), and therefore you will also find many people with Slavic ancestors there. Some of our most famous poets and politicians were of Slavic descent, for example. The Slavs played a somewhat similar role in Hungarian culture as the Celts did in that of England/Britain.
I've been told there is some Slavic influence on Romanian, but it still sounds to my ears like a very romantic language (as a matter of fact, when I flipped to a Romanian television program once, I mistakenly thought it was a strange dialect of Spanish for a few seconds).
I wonder, while we're discussing Eastern European languages, why Albanian is so different from any languages in the area?
Ben,
There are still clouds of mystery surrounding Albanian. It is thought to have descended from the language of the Illyrians, or another "aboriginal" group of the Balkans. It does have some Latin and Slavic loanwords, though (and shares some cognates with Romanian, by the way). One of such loanwords is "peshq", from Latin "pisces" ("fish"). The Albanians have always led an isolated lifestyle in the mountains, that may also account for the very distinctive features of their language.
About the comment on Romanian, indeed, it is a little like Spanish or Italian. What I pesonally like about it is very expressive, and some of its phrases are very lyrical. My personal favourite is the expression "cu noaptea in cap", meaning "very early", but literally "with the night in one's head".
Sorry, it should have been: "What I peRsonally like about it is THAT IT IS very expressive".
Until the 19th Century, Romanian had many more Slavic-origin words. In those nationalist days of Romania's early independence, there was a deliberate effort to replace these words with Latin-, Italian- and French-based ones.
So you often end up with very "old" words from Latin and "new" Latin words sourced in the 19th Century.