Well, the Ancient name of the Balkan region-(that is to say, dating back 1500 plus years ago), was called, "Illyria". Before the Turks arrived into "The Balkans" during the 1400's and before the Slavs arrived into this same region nearly 1000 years earlier, this region-(excluding Romania, Hungary, Greece & Anatolia/Asia Minor) was the greater Illyrian region.
The Illyrians were the ancient ancestors of the present-day Albanian peoples. Although today's Albania is a fairly small country-(even when adding the largely Albanian region/quasi-state of Kosovo), the region of Illyria encompassed a greater amount of territory throughout Southeast Europe. The majority of present-day Albania, Kosovo, and much of the South Slavic interior-(what was known as "Yugoslavia" throughout much of the 20th century), was, "once upon a time", some 1500 plus years ago, Ancient Albania-(or Illyria). Although Albanians were the majority population in this region 1500 plus years ago, both a minority of Romans and Greeks had been living in or near greater Illyria for centuries.
When the Slavs invaded and proliferated throughout Eastern Europe, they traveled as far as the Peloponnese in Southern Greece, though much of their demographic concentration was in Central Europe and Illyria. The Slavic conquest and
settlement of greater Illyria displaced many indigenous Illyrians to neighboring regions, some Illyrians were assimilated into the Slavic culture over time and the centuries old Illyrian region would, in effect, become populated with various South Slavic peoples, from Slovenia, to Northern Bulgaria.
When the Ottomans arrived in the 1400's, they nicknamed the older Illyrian region as, "The Balkans"-(which literally translates as, "the mountainside region", due to the very high mountainous peaks that dominate the landscapes of various Southeast European countries).