The institutions of the European Union have defined the "Western Balkans" as the Balkan area that includes countries that are not members of the European Union, while others refer to the geographical aspects.
From 1920 until World War II, Italy included Istria and some Dalmatian areas (like Zara, today's Zadar) that are within the general definition of the Balkan peninsula.
The current territory of Italy includes only the small area around Trieste inside the Balkan Peninsula.
The Balkan Peninsula is bordered by the Adriatic Sea on the northwest, the Ionian Sea on the southwest, the Aegean Sea in the south and southeast, and the Black Sea on the east and northeast.
The northern border of the peninsula is variously defined.
In the languages of the region, the peninsula is known as: The Balkan Peninsula is surrounded by the Adriatic Sea to the west, the Mediterranean Sea (including the Ionian and Aegean seas) and the Marmara Sea to the south and the Black Sea to the east.
Its northern boundary is often given as the Danube, Sava and Kupa Rivers.
Most of the area is covered by mountain ranges running from the northwest to southeast.
The main ranges are the Balkan mountains, running from the Black Sea coast in Bulgaria to its border with Serbia, the Rhodope mountains in southern Bulgaria and northern Greece, the Dinaric Alps in Bosnia and Herzegovina, Croatia and Montenegro, the Šar massif which spreads from Albania to Macedonia, and the Pindus range, spanning from southern Albania into central Greece and the Albanian Alps.
Zeus injured Typhon with a thunder bolt and Typhon's blood fell on the mountains, from which they got their name.