Bulgaria in the context of Rock formation

Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to the east. The Aegean Sea lies to the east of the mainland, the Ionian Sea to the west, and the Sea of Crete and the Mediterranean Sea to the south. Greece has the longest coastline on the Mediterranean basin, spanning thousands of islands and nine traditional geographic regions. It has a population of over 10 million. Athens is the nation's capital and largest city, followed by Thessaloniki, Patras and Heraclion.

Greece is considered the cradle of Western civilisation and the birthplace of democracy, Western philosophy, Western literature, historiography, political science, major scientific and mathematical principles, theatre, and the Olympic Games. The Ancient Greeks were organised into independent city-states, or poleis (singular polis), that spanned the Mediterranean and Black seas. Philip II of Macedon united most of present-day Greece in the fourth century BC, with his son Alexander the Great conquering much of the known ancient world from the Near East to northwestern India. The subsequent Hellenistic period saw the height of Greek culture and influence in antiquity. Greece was annexed by Rome in the second century BC and became an integral part of the Roman Empire and its continuation, the Byzantine Empire, where Greek culture and language were dominant. The Greek Orthodox Church, which emerged in the first century AD, helped shape modern Greek identity and transmitted Greek traditions to the wider Orthodox world.

The Balkans (/ˈbɔːlkənz/ BAWL-kənz, /ˈbɒlkənz/ BOL-kənz), corresponding partially with the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the whole of Bulgaria. The Balkan Peninsula is bordered by the Adriatic Sea in the northwest, the Ionian Sea in the southwest, the Aegean Sea in the south, the Turkish straits in the east, and the Black Sea in the northeast. The northern border of the peninsula is variously defined. The highest point of the Balkans is Musala, 2,925 metres (9,596 ft), in the Rila mountain range, Bulgaria.

The concept of the Balkan Peninsula was created by the German geographer August Zeune in 1808, who mistakenly considered the Balkan Mountains the dominant mountain system of southeastern Europe spanning from the Adriatic Sea to the Black Sea. In the 19th century the term Balkan Peninsula was a synonym for Rumelia, the parts of Europe that were provinces of the Ottoman Empire at the time. It had a geopolitical rather than a geographical definition, which was further promoted during the creation of Yugoslavia in the early 20th century. The definition of the Balkan Peninsula's natural borders does not coincide with the technical definition of a peninsula; hence modern geographers reject the idea of a Balkan Peninsula, while historical scholars usually discuss the Balkans as a region. The term has acquired a stigmatized and pejorative meaning related to the process of Balkanization. The region may alternatively be referred to as Southeast Europe.

North Macedonia, officially the Republic of North Macedonia, is a landlocked country in Southeast Europe. It shares land borders with Greece to the south, Albania to the west, Bulgaria to the east, Kosovo to the northwest and Serbia to the north. It constitutes approximately the northern third of the larger geographical region of Macedonia. Skopje, the capital and largest city, is home to a quarter of the country's population of over 1.83 million. The majority of the residents are ethnic Macedonians, a South Slavic people. Albanians form a significant minority at around 25%, followed by Turks, Roma, Serbs, Bosniaks, Aromanians and a few other minorities.

The region's history begins with the kingdom of Paeonia. In the late sixth century BC, the area was subjugated by the Persian Achaemenid Empire, then incorporated into the Kingdom of Macedonia in the fourth century BC. The Roman Republic conquered the region in the second century BC and made it part of its larger province of Macedonia. The area remained part of the Byzantine Empire, but was often raided and settled by Slavic tribes beginning in the sixth century CE. Following centuries of contention between the Bulgarian, Byzantine, and Serbian Empires, it was part of the Ottoman Empire from the mid-14th until the early 20th century, when, following the Balkan Wars of 1912 and 1913, the modern territory of North Macedonia came under Serbian rule.

Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia, Armenia, Azerbaijan, and Iran to the east; Iraq, Syria, and the Mediterranean Sea to the south; and the Aegean Sea, Greece, and Bulgaria to the west. Turkey is home to over 85 million people; most are ethnic Turks, while Kurds are the largest ethnic minority. Officially a secular state, Turkey has a Muslim-majority population. Ankara is Turkey's capital and second-largest city. Istanbul is its largest city and economic center. Other major cities include İzmir, Bursa, and Antalya.

First inhabited by modern humans during the Late Paleolithic, present-day Turkey was home to various ancient peoples. The Hattians were assimilated by the Hittites and other Anatolian peoples. Classical Anatolia transitioned into cultural Hellenization after Alexander the Great's conquests, and later Romanization during the Roman and Byzantine eras. The Seljuk Turks began migrating into Anatolia in the 11th century, starting the Turkification process. The Seljuk Sultanate of Rum ruled Anatolia until the Mongol invasion in 1243, when it disintegrated into Turkish principalities. Beginning in 1299, the Ottomans united the principalities and expanded. Mehmed II conquered Constantinople (modern-day Istanbul) in 1453. During the reigns of Selim I and Suleiman the Magnificent, the Ottoman Empire became a global power. From 1789 onwards, the empire saw major changes, reforms, centralization, and rising nationalism while its territory declined.

Greece is a country in Southeastern Europe, on the Balkan Peninsula. It is bordered to the north by Albania, North Macedonia and Bulgaria; to the east by Turkey, and is surrounded to the east by the Aegean Sea, to the south by the Cretan and the Libyan seas, and to the west by the Ionian Sea which separates Greece from Italy.

The country consists of an extremely rough, mountainous, peninsular mainland jutting out into the Mediterranean Sea at the southernmost tip of the Balkans, and two smaller peninsulas projecting from it:the Chalkidiki and the Peloponnese, which is joined to the mainland by the Isthmus of Corinth. Greece also has many islands, of various sizes, the largest being Crete, Euboea, Lesvos, Rhodes, Chios, Kefalonia, and Corfu; groups of smaller islands include the Dodecanese and the Cyclades. According to the CIA World Factbook, Greece has 13,676 kilometres (8,498 mi) of coastline, the largest in the Mediterranean Basin.

The Black Sea is a marginal sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.

The Black Sea, not including the Sea of Azov, covers 436,400 km (168,500 sq mi), has a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km (131,000 cu mi).Most of its coasts ascend rapidly.These rises are the Pontic Mountains to the south, bar the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north.In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end of the Balkan Mountains; and the Dobruja Plateau considerably farther north. The longest east–west extent is about 1,175 km (730 mi). Important cities along the coast include (clockwise from the Bosporus) the northern suburbs of Istanbul, Burgas, Varna, Constanța, Odesa, Yalta, Kerch, Yevpatoria, Sevastopol, Novorossiysk, Sochi, Poti, Batumi, Rize, Trabzon, Ordu, Simferopol, Samsun and Zonguldak.

Under the reign of Philip II (359–336 BC), the ancient kingdom of Macedonia, initially at the periphery of classical Greek affairs, came to dominate Ancient Greece in the span of less than 25 years, largely thanks to the character and policies of its king. In addition to utilising effective diplomacy and marriage alliances to achieve his political aims, Philip II was responsible for reforming the ancient Macedonian army into an effective fighting force. The Macedonian phalanx became the hallmark of the Macedonian army during his reign and the subsequent Hellenistic period. His army and engineers also made extensive use of siege engines. Chief among Philip's Thracian enemies was the ruler Kersebleptes, who may have coordinated a temporary alliance with Athens. In a series of campaigns stretching from 356 to 340 BC, Philip II managed to ultimately subjugate Kersebleptes as a tributary vassal, conquering much of Thrace in the process. Philip II also fought against the Illyrian king Bardylis, who threatened Macedonia proper, and against Grabos II and Pleuratus in Illyria (centred in modern-day Albania). In his newly conquered territories, he founded new cities such as Philippi, Philippopolis (modern Plovdiv, Bulgaria), Herakleia Sintike (Pirin Macedonia, Bulgaria), and Herakleia Lynkestis (modern Bitola, North Macedonia).

Philip II eventually campaigned against the city-state of Athens and her allies in the Aegean region, as well as Thebes after the decline of its hegemony in mainland Greece. In the defence of the Amphictyonic League of Delphi and in conjunction with the Thessalian League, Macedonia became a key player in the Third Sacred War (356–346 BC), defeating the Phocians, commanded by Onomarchus, at the Battle of Crocus Field in 352 BC. While poised to launch a direct assault on Athens in 346 BC, the Macedonian king was met with an Athenian embassy that arranged the Peace of Philocrates. As a result, Macedonia and Athens became allies, yet Athens was forced to relinquish its claims to the city of Amphipolis (in modern-day Central Macedonia).

Macedonia (/ˌmæsɪˈdoʊniə/ MASS-ih-DOH-nee-ə; Greek: Μακεδονία, romanized: Makedonía, pronounced [maceðoˈni.a] ) is a geographic and former administrative region of Greece, in the southern Balkans. Macedonia is the largest and second-most-populous geographic region in Greece, with a population of 2.36 million (as of 2020). Part of Northern Greece, it is highly mountainous, with major urban centres such as Thessaloniki and Kavala being concentrated on its southern coastline. Greek Macedonia encompasses entirely the southern part of the wider region of Macedonia, making up 51% of the total area of that region. Additionally, it widely constitutes Greece's borders with three countries: Albania to the northwest, North Macedonia to the north, and Bulgaria to the northeast.

Greek Macedonia incorporates most of the territories of Macedon, a Greek kingdom ruled by the Argeads, whose most celebrated members were Alexander the Great and his father Philip II. Before the expansion of Macedonia under Philip in the 4th century BC, the kingdom of the Macedonians covered an area corresponding roughly to the administrative regions of Western and Central Macedonia in modern Greece. The name Macedonia was later applied to a number of widely-differing administrative areas in the Roman and Byzantine empires. With the gradual conquest of south-eastern Europe by the Ottomans in the late 14th century, the name of Macedonia disappeared as an administrative designation for several centuries and was rarely displayed on maps. With the rise of nationalism in the Ottoman Empire, the name Macedonia was revived in the nineteenth century as a geographical term, and for educated Greeks it corresponded to the ancient historical land. The economic ascent of Thessaloniki and of the other urban centres of Macedonia coincided with the cultural and political renaissance of the Greeks. The leader and coordinator of the Greek Revolution in Macedonia was Emmanouel Pappas, today considered a Greek hero along with the unnamed Macedonians that fought with him.

East Thrace or Eastern Thrace, also known as Turkish Thrace or European Turkey, is the part of Turkey that is geographically in Southeast Europe. Turkish Thrace accounts for 3.03% of Turkey's land area and 15% of its population. The largest city is Istanbul, which straddles the Bosporus between Europe and Asia. East Thrace is of historic importance as it is next to a major sea trade corridor and constitutes what remains of the once-vast Ottoman region of Rumelia. It is currently also of specific geostrategic importance because the sea corridor, which includes two narrow straits, provides access to the Mediterranean Sea from the Black Sea for the navies of five countries: Russia, Ukraine, Romania, Bulgaria, and Georgia. The region also serves as a future connector of existing Turkish, Bulgarian, and Greek high-speed rail networks.Due to the guest worker agreement with Turkey and Germany, some Turks in Germany originally come from Eastern Thrace, mostly from the Kırklareli Province.

The Balkan mountain range is located in the eastern part of the Balkan peninsula in Southeastern Europe. It is conventionally taken to begin at the peak of Vrashka Chuka on the border between Bulgaria and Serbia. It then runs for about 560 kilometres (350 mi), first in a south-easterly direction along the border, then eastward across Bulgaria, forming a natural barrier between the northern and southern halves of the country, before finally reaching the Black Sea at Cape Emine. The mountains reach their highest point with Botev Peak at 2,376 metres (7,795 ft).

In much of the central and eastern sections, the summit forms the watershed between the drainage basins of the Black Sea and the Aegean. A prominent gap in the mountains is formed by the predominantly narrow Iskar Gorge, a few miles north of the Bulgarian capital, Sofia. The karst relief determines the large number of caves, including Magura, featuring the most important and extended European post-Palaeolithic cave painting, Ledenika, Saeva dupka, Bacho Kiro, etc. The most notable rock formation are the Belogradchik Rocks in the west.

Musala (Bulgarian: Мусала [mosɐˈɫa]); from Arabic through Ottoman Turkish: from Musalla, "near God" or "place for prayer" is the highest peak in the Rila Mountains, as well as in Bulgaria and the entire Balkan Peninsula, standing at 2,925.42 metres (9,597.8 ft).

With a topographic prominence of 2,473 metres (8,114 ft), Musala is also the 6th highest peak by topographic prominence in mainland Europe. It is also the 3rd most topographically isolated major peak in Continental Europe.

Rila (Bulgarian: Рила, pronounced [ˈriɫɐ]) is the highest mountain range of Bulgaria, the Balkan Peninsula, and of Southeast Europe. It is situated in southwestern Bulgaria and forms part of the Rila–Rhodope Massif. The highest summit is Musala at an elevation of 2,925 m which makes Rila the sixth highest mountain range in Europe after the Caucasus, the Alps, Sierra Nevada, the Pyrenees and Mount Etna, and the highest one between the Alps and the Caucasus. It spans a territory of 2,629 km with an average elevation of 1487 m. The mountain is believed to have been named after the river of the same name, which comes from the Old Bulgarian verb "рыти" meaning "to grub".

Rila has abundant water resources. Some of the Balkans' longest and deepest rivers originate from Rila, including the Maritsa, Iskar and Mesta rivers. Bulgaria's main water divide separating the Black Sea and the Aegean Sea drainage systems follows the main ridge of Rila. The mountain range is dotted with almost 200 glacial lakes such as the renowned Seven Rila Lakes, and is rich in hot springs in the fault areas at the foothills, including the hottest spring in South-eastern Europe in Sapareva Banya.

Serbia, officially the Republic of Serbia, is a landlocked country in Southeast and Central Europe. Located in the Balkans, it borders Hungary to the north, Romania to the northeast, Bulgaria to the southeast, North Macedonia to the south, Croatia to the northwest, Bosnia and Herzegovina to the west, and Montenegro to the southwest. Serbia also claims to share a border with Albania through the disputed territory of Kosovo. Serbia has about 6.6 million inhabitants, excluding Kosovo. Serbia's capital, Belgrade, is also the largest city in the country.

Continuously inhabited since the Paleolithic age, the territory of modern-day Serbia faced Slavic migrations in the 6th century. Several regional states were founded in the Early Middle Ages and were at times recognised as tributaries to the Byzantine, Frankish and Hungarian kingdoms. The Serbian Kingdom obtained recognition by the Holy See and Constantinople in 1217, reaching its territorial apex in 1346 as the Serbian Empire. By the mid-16th century, the Ottoman Empire annexed the entirety of modern-day Serbia; their rule was at times interrupted by the Habsburg Empire, which began expanding towards Central Serbia from the end of the 17th century while maintaining a foothold in Vojvodina. In the early 19th century, the Serbian Revolution established the nation-state as the region's first constitutional monarchy, which subsequently expanded its territory.

Macedonia (/ˌmæsɪˈdoʊniə/ MASS-ih-DOH-nee-ə) is a geographical and historical region of the Balkan Peninsula in Southeast Europe. Its boundaries have changed considerably over time; however, it came to be defined as the modern geographical region by the mid-19th century. Today the region is considered to include parts of six Balkan countries: all of North Macedonia, large parts of Greece and Bulgaria, and smaller parts of Albania, Serbia, and Kosovo. Greek Macedonia comprises about half of Macedonia's area and population.

Its oldest known settlements date back approximately to 7,000 BC. From the middle of the 4th century BC, the Kingdom of Macedon became the dominant power on the Balkan Peninsula; since then Macedonia has had a diverse history.

In antiquity, Paeonia or Paionia (Ancient Greek: Παιονία, romanized: Paionía) was the land and kingdom of the Paeonians (or Paionians; Ancient Greek: Παίονες, romanized: Paíones).

The exact original boundaries of Paeonia, like the early history of its inhabitants, are obscure, but it is known that it roughly corresponds to most of present-day North Macedonia and north-central parts of Greek Macedonia before the expansion of Macedon (i.e. probably the Greek municipalities of Paionia (excluding the village of Evropos), Almopia, Sintiki, Irakleia, and Serres), and a small part of south-western Bulgaria. Ancient authors placed it south of Dardania (an area corresponding to modern-day Kosovo and northern North Macedonia), west of the Thracian mountains, and east of the southernmost Illyrians. It was separated from Dardania by the mountains through which the Vardar river passes from the field of Scupi (modern Skopje) to the valley of Bylazora (near modern Sveti Nikole).

Romania is a country located at the crossroads of Central, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to the east, and the Black Sea to the southeast. It has a mainly continental climate, and an area of 238,397 km (92,046 sq mi) with a population of 19 million people. Romania is the twelfth-largest country in Europe and the sixth-most populous member state of the European Union. Europe's second-longest river, the Danube, empties into the Danube Delta in the southeast of the country. The Carpathian Mountains cross Romania from the north to the southwest and include Moldoveanu Peak, at an altitude of 2,544 m (8,346 ft). Bucharest is the country's capital, largest urban area, and financial centre. Other major urban areas include Cluj-Napoca, Timișoara, Iași, Constanța and Brașov.

Settlement in the territory of modern Romania began in the Lower Paleolithic, later becoming the Dacian Kingdom before Roman conquest and Romanisation. The modern Romanian state was formed in 1859 with the unification of Moldavia and Wallachia under Alexandru Ioan Cuza, becoming the Kingdom of Romania in 1881 under Carol I of Romania. Romania gained independence from the Ottoman Empire in 1877, formalised by the Treaty of Berlin. After World War I, Transylvania, Banat, Bukovina, and Bessarabia joined the Old Kingdom, forming Greater Romania, which reached its largest territorial extent. In 1940, under Axis pressure, Romania lost territories to Hungary, Bulgaria, and the Soviet Union. Following the 1944 Romanian coup d'état, Romania switched sides to join the Allies. After World War II, it regained Northern Transylvania through the Paris Peace Treaties. Under Soviet occupation, King Michael I was forced to abdicate, and Romania became a socialist republic and Warsaw Pact member. After the uniquely violent Romanian revolution in December 1989, Romania began a transition to liberal democracy and a market economy.

Sofia is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain, in the western part of the country. The city is built west of the Iskar river and has many mineral springs, such as the Sofia Central Mineral Baths. It has a humid continental climate.

Known as Serdica in antiquity, Sofia has been an area of human habitation since at least 7000 BC. The recorded history of the city begins with the attestation of the conquest of Serdica by the Roman Republic in 29 BC from the Celtic tribe Serdi. During the decline of the Roman Empire, the city was raided by Huns, Visigoths, Avars, and Slavs. In 809, Serdica was incorporated into the First Bulgarian Empire by Khan Krum and became known as Sredets. In 1018, the Byzantines ended Bulgarian rule until 1194, when it was reincorporated by the Second Bulgarian Empire. Sredets became a major administrative, economic, cultural and literary hub until its conquest by the Ottomans in 1382. From 1530 to 1836, Sofia was the regional capital of Rumelia Eyalet, the Ottoman Empire's largest and most important province. Bulgarian rule was restored in 1878. Sofia was selected as the capital of the Third Bulgarian State in the next year, ushering a period of intense demographic and economic growth.