Short answers, pulled from the story.
The word Balkan likely derives from the Turkish word balk, meaning mud, or possibly from Persian bala-khana, meaning big high house. In Ottoman Turkish and modern Turkish, balkan means a chain of wooded mountains. The name was first recorded on an Arab map in the early 14th century and entered English literature through the traveler John Bacon Sawrey Morritt at the end of the 18th century.
The concept of the Balkan Peninsula was created by the German geographer August Zeune in 1808. Zeune mistakenly believed the Balkan Mountains ran as the dominant spine of southeastern Europe from the Adriatic Sea to the Black Sea. Modern geographers have since rejected the idea of a Balkan Peninsula because the region's land border is longer than its sea border, failing the technical definition of a peninsula.
The Balkans are home to some of the oldest known cultures in Europe. The Vinca culture developed a form of proto-writing called the Old European script before the Sumerians and Minoans, with its bulk of symbols created between 4500 and 4000 BC. The earliest Neolithic culture in the region, the Kakanj culture, appeared in central Bosnia and covered periods from 6795 to 4900 BC.
World War I was sparked in Sarajevo, the capital of Bosnia and Herzegovina, when members of Young Bosnia assassinated Archduke Franz Ferdinand of Austria, the Austro-Hungarian heir, in 1914. Young Bosnia was a revolutionary organization with predominantly Serb and pro-Yugoslav members. The assassination triggered a war between Austria-Hungary and Serbia that, through existing chains of alliances, escalated into World War I.
By 1900, some 80,000 Jews lived in Thessaloniki, making up more than half of the city's population at the time. The Jewish communities of the Balkans were among the oldest in Europe and were largely Sephardic Jews. The vast majority were killed during the Holocaust, with an exception being the Bulgarian Jews, whom Boris III of Bulgaria sent to forced labor camps rather than Nazi concentration camps.
Greece joined the EU in 1981, Slovenia in 2004, Bulgaria and Romania in 2007, and Croatia in July 2013. Several other Balkan countries, including Turkey, North Macedonia, Montenegro, Albania, and Serbia, have been accepted as candidates or started accession negotiations, though Serbia's process has stalled over the recognition of Kosovo as an independent state.