Much of this area is mountainous and all of it lies on Europe's Balkan Peninsula. Montenegro's and Albania's wests front the Adriatic Sea. While the Dinaric(5) Alps give the former a rugged coast and no river mounths, Albania has lowlands and rivers flowing to the sea.
Further inland is an important north-south travel corrider: the Vardar, flowing from the southeast into Greece on its way to the Aegean Sea, and the Morava, starting from near the Vardar's head and flowing from near the Serbo-Macedonian border to to meet the Danube(6) north of the mountains.
The Danube flows across northern Serbia, receiving the Sava from about due west and the Tisza(7) from the north.
There are three large lakes: Scutari(8) on the Montenegro-Albanian border, Ohrid on the Macedonian-Albanian frontier and Prespa where Albanian, Macedonia and Serbia meet.
A slight majority--almost all living in Serbia and Montenegro--speak Serbo-Croatian. Albanian(9) speakers account for more than a quarter and less than a third of the total, and Macedonians--mostly in Macedonia--for less than one in ten. A miscellany of languages accounts for six to 11 percent.
Less than two in three are Christian, less than one in three Sunni Moslem and the rest--about eight percent--mostly non-observant or aetheist. Of the Christians, more than one in eight are Roman Catholics, with almost all the rest Orthodox. Of the Orthodox Christians about eight in ten are Serbian Orthdox and about one in eight Macedonian Orthodox.
Belgrad(10) is the only city with more than a million people. It serves as the capital of the nominally united country of Serbia and Montenegro, situated at the confluence of the Sava and the Danube. Its religious importance is shown by its being the seat of the Serbian Orthodox Christian patriarch and of a Roman Catholic Christian archbishop, as well as having the tomb of Sheikh Mustapha and a Jewish historical museum.
About 6000 years ago Indo-European dialects may have been spoken here--they certainly were to the northeast. Around 3000 years ago Illyrian--possibly the ancestor of Albanian--was spoken here. Celtic languages were spoken away from the Adriatic coast when Rome conquered the area. The conquest spread Latin, which may or may not have left traces in today's regional languages, though none are descendents. Slavonic languages moved south into the area in the seventh to ninth centuries, giving rise to the South Slavonic languages of Serbo-Croatian and Macedonian.
Before Christianization, the Illyrians and Celts practiced religions similar to those common to Indo-Euorpeans, but the local specifics are unknown to me. Christianization occured initially during the Roman Empire, with the invading South Slavs being converted by the empire's successor, the Byzantine Empire. Islam arrived with Turkish conquest in the first half of the last millenium.
northwest and north
northeast
southeast
south
south from southernmost Albania
west from southern, but not southernmost, Albania
southwest of Montenegro and west of Albania
(1) Shqiperi in Albanian.
(2) Makedonija in Macedonian.
(3) Srbija in Serbo-Croatian.
(4) Crna Gora in Serbo-Croatian. Translates as Black Mountain.
(5) Dinara in Serbo-Croatian.
(6) Dunav in Serbo-Croatian.
(7) Tisa in Serbo-Croatian.
(8) Shkodra in Albanian and Skadar in Serbo-Croatian.
(9) Some consider Gheg Albanian and Tosk Albanian as separate languages. Gheg speakers--mostly in the Kosovo part of Serbia and Montenegro--are about a third of Albanians; Tosk speakers--all in Albania--are the rest.
(10) Beograd in Serbo-Croatian. It translates as White Mountain.