A History of Bulgaria

• Introduction
• Chapter 1 The Ancient Lands: Thracians, Greeks, and Romans
• Chapter 2 The Great Migrations: Slavs and the Proto-Bulgarians
• Chapter 3 The Dawn of a Khanate: The First Bulgarian Empire
• Chapter 4 The Golden Age: The Reign of Tsar Simeon I
• Chapter 5 The Spread of Letters: Saints Cyril and Methodius and Their Legacy
• Chapter 6 A Century of Decline and the Fall to Byzantium
• Chapter 7 The Asen Dynasty: The Rise of the Second Bulgarian Empire
• Chapter 8 The Apex of Power: Ivan Asen II and Imperial Ambitions
• Chapter 9 Medieval Bulgarian Culture and the Tarnovo Artistic School
• Chapter 10 Internal Division and the Ottoman Onslaught
• Chapter 11 Under the Crescent: Five Centuries of Ottoman Rule
• Chapter 12 The National Revival: The Awakening of a Nation
• Chapter 13 The Fight for Spiritual Independence: The Bulgarian Exarchate
• Chapter 14 The April Uprising: A Rebellion Forged in Blood
• Chapter 15 Liberation and the Treaty of San Stefano
• Chapter 16 The Third Bulgarian State: Prince Alexander I and the Unification
• Chapter 17 The Balkan Wars: Expansion and Conflict
• Chapter 18 Bulgaria in the First World War: A Nation on the Wrong Side
• Chapter 19 The Interwar Period: Political Instability and Agrarianism
• Chapter 20 A Kingdom Divided: Bulgaria in the Second World War
• Chapter 21 The People's Republic: The Rise of Communism
• Chapter 22 The Zhivkov Era: Four Decades of Socialist Rule
• Chapter 23 The Fall of the Iron Curtain: The Transition to Democracy
• Chapter 24 A New Beginning: Navigating a Post-Communist World
• Chapter 25 Bulgaria in the 21st Century: NATO and the European Union

There are places on Earth that seem destined by their very geography to be crossroads. They are the lands where trade routes converge, where armies clash, and where ideas from distant cultures meet, mingle, and sometimes violently collide. Bulgaria, nestled in the eastern heart of the Balkan Peninsula, is quintessentially such a place. For millennia, this territory, defined by the broad Danube River to the north, the welcoming shores of the Black Sea to the east, and rugged mountain ranges that have sheltered and divided its people, has been a stage for some of history's most compelling dramas. It is a story of great empires rising and falling, of fierce battles for faith and freedom, and of a tenacious cultural identity that has weathered storms that would have extinguished many others. This book aims to tell that story, to trace the long, turbulent, and fascinating journey of the Bulgarian lands and people from the deepest echoes of antiquity to their modern-day place in the European family.

The narrative of this land does not begin with the Bulgarians themselves. Long before the name "Bulgaria" was ever uttered, this was the domain of the Thracians, an ancient and enigmatic people whose legacy is etched into the very soil. Known to the ancient Greeks as fierce warriors, skilled horsemen, and creators of breathtakingly intricate gold and silver treasures, the Thracians were a collection of tribes who, despite their cultural brilliance, rarely achieved political unity. Figures of myth and legend like Orpheus, the musician who could charm beasts and gods, and Spartacus, the gladiator who shook the foundations of Rome, emerged from Thracian stock. For centuries, their kingdoms flourished, engaging in complex relationships of trade, culture, and conflict with their Greek neighbors and the mighty Persian Empire to the east. Eventually, the might of Rome proved irresistible, and by the 1st century AD, the Thracian lands were absorbed into the Roman Empire, becoming the provinces of Moesia and Thracia. The Romans, as was their custom, brought roads, cities, and laws, leaving a lasting imprint on the landscape and its people, who gradually became Christianized and Romanized citizens of a vast, multicultural empire.

The decline of Roman power heralded an era of profound change across Europe, and the Balkans became a maelstrom of migrating peoples. Into this vacuum, beginning around the 6th century AD, flowed waves of Slavic tribes from the north. They were agriculturalists who settled the fertile plains and valleys, fundamentally and permanently altering the demographic makeup of the region. The Thracian and Romanized inhabitants were largely assimilated by these numerous newcomers, creating the Slavic bedrock of the future Bulgarian nation. This new reality, however, was soon to be transformed by the arrival of another, very different group: the Bulgars. Hailing from the steppes of Central Asia, the Bulgars were a Turkic, semi-nomadic people, renowned for their martial prowess and sophisticated state organization under a ruling Khan. Under the leadership of Khan Asparuh, one group of Bulgars crossed the Danube in the late 7th century, seeking new lands after their confederation of "Great Bulgaria" to the north of the Black Sea was shattered by the Khazars.

In a decisive moment for European history, Khan Asparuh’s forces defeated a Byzantine army in 680 AD and established a new state in the lands south of the Danube. The following year, in 681, the powerful Byzantine Empire was compelled to sign a peace treaty, officially recognizing the new Khanate. This event marks the birth of the First Bulgarian Empire, one of the oldest states in Europe. What followed was a remarkable process of fusion. The numerically smaller but militarily and politically dominant Bulgars formed a ruling elite over the vast Slavic population. Over the next two centuries, these two distinct peoples gradually coalesced, with the Slavic language and customs prevailing, but the state retaining the name of its Bulgar founders. This unique synthesis of Bulgar statecraft and Slavic culture created a powerful and dynamic new entity on the European stage, one that would soon become a formidable rival to the Byzantine Empire itself.

The 9th and 10th centuries witnessed developments that would forever define Bulgaria's identity and its immense contribution to European civilization. A pivotal moment came in 864 AD under the reign of Knyaz Boris I, who made the strategic and profound decision to adopt Orthodox Christianity as the state religion. This monumental step was not merely a spiritual one; it was a geopolitical masterstroke that aligned Bulgaria with the great cultural sphere of Byzantium while also providing a powerful tool for unifying his still-diverse subjects under a common faith and identity. Boris I's foresight was further demonstrated when he welcomed the disciples of Saints Cyril and Methodius. These missionaries had developed the first Slavic alphabet, the Glagolitic script, but were driven out of Great Moravia. In Bulgaria, their followers found a fertile ground for their work, leading to the development of a new, more practical script at the Preslav Literary School: the Cyrillic alphabet. This new alphabet, tailored to the sounds of the Slavic tongue, became the vehicle for a flourishing of Christian literature and learning in a language the people could understand, laying the foundation for the spiritual and cultural independence of the entire Slavic Orthodox world.

This period of cultural blossoming reached its zenith during the reign of Tsar Simeon I (893-927), a period rightly known as the "Golden Age" of Bulgarian culture. Educated in Constantinople, Simeon was a ruler of vast ambition and refined taste, aiming to create a civilization that could rival Byzantium in both power and splendor. His reign was marked by spectacular military successes that expanded Bulgarian territory from the Black Sea to the Adriatic and Aegean. He assumed the title of Tsar (Emperor), directly challenging the supremacy of the Byzantine Emperor. But his legacy lies equally in his patronage of arts and letters. The capital was moved to Preslav, which was built to be a magnificent imperial city filled with churches and palaces. Here, a circle of scholars translated Byzantine texts into Old Bulgarian, creating a rich body of religious and secular literature that would be disseminated across the Slavic world, from Kievan Rus' to Serbia. The development and spread of the Cyrillic script during this era stands as one of Bulgaria's most enduring gifts to the world, shaping the cultural landscape of Eastern Europe for over a millennium.

No empire lasts forever, and the First Bulgarian Empire, after its glorious peak, entered a period of decline. Beset by internal strife and the relentless pressure of a resurgent Byzantine Empire, the state weakened. In 1014, the Byzantine Emperor Basil II, who would earn the grim epithet "the Bulgar-Slayer," inflicted a catastrophic defeat on the Bulgarian army at the Battle of Kleidion. By 1018, the last vestiges of Bulgarian resistance were crushed, and the country was fully absorbed into the Byzantine Empire, losing its independence for nearly two centuries. Yet, the memory of statehood and the distinct cultural identity forged during the Golden Age did not die. Byzantine rule was often harsh, with heavy taxes and the imposition of Greek clergy, which fueled resentment. In 1185, a major uprising led by two aristocratic brothers, Asen and Peter, successfully cast off Byzantine control. They established the Second Bulgarian Empire, with its capital at the well-fortified city of Tarnovo.

Under the rulers of the Asen dynasty, particularly Tsar Ivan Asen II (1218-1241), the Second Bulgarian Empire became the dominant power in Southeastern Europe for a time. Its influence once again stretched across a vast swathe of the Balkans, encompassing territories in modern-day Albania, Greece, and Macedonia. Tarnovo became a vibrant political, religious, and cultural center, often referred to as the "Third Rome." This period saw a renaissance in art and architecture, with the Tarnovo Artistic School producing remarkable frescoes and icons. However, this resurgence was not to last. Following the death of Ivan Asen II, the empire was weakened by a succession of short-lived rulers, internal revolts, and devastating Mongol invasions from the north. By the late 14th century, the once-mighty state had fractured into smaller, competing principalities. This fragmentation left them vulnerable to a new and formidable power rising from the southeast: the Ottoman Turks. One by one, the Bulgarian strongholds fell, culminating in the capture of the capital, Tarnovo, in 1393 after a grueling siege. By 1396, the last of the Bulgarian lands were subjugated, marking the end of medieval Bulgarian independence and the beginning of a period of foreign rule that would last for five long centuries.

The nearly 500 years of Ottoman rule represent a profoundly transformative and often traumatic period in Bulgarian history. The old Bulgarian aristocracy was eliminated, and the independent Bulgarian church was placed under the authority of the Greek Patriarchate in Constantinople. Bulgarian lands were reorganized into the Ottoman administrative system, and a significant number of Turks settled in the region. For much of this period, the Bulgarian people were largely an agrarian society, living as non-Muslim subjects (rayah) within a vast Islamic empire. While the early centuries of stable Ottoman power were in some ways less chaotic than the final years of medieval feudalism, cultural and national expression was suppressed. Yet, beneath the surface, the Bulgarian language, Orthodox faith, and folk traditions were preserved in villages and remote monasteries, forming a reservoir of cultural memory that would prove vital for the future.

By the 18th century, as the power of the Ottoman Empire began to wane, the first stirrings of a national awakening began to ripple through Bulgarian society. This period, known as the Bulgarian National Revival, was a time of profound cultural and intellectual rebirth. It began not with armies, but with a book: the Istoriya Slavyanobolgarskaya (Slav-Bulgarian History), written in 1762 by a monk named Paisiy of Hilendar. This passionate work reminded a people of their glorious past, of their mighty tsars and saints, and sparked a renewed sense of national pride. The Revival saw the establishment of the first Bulgarian-language schools, the printing of books, and a growing demand for cultural and spiritual autonomy. This struggle culminated in a major victory in 1870 with the establishment of an independent Bulgarian Exarchate, which restored the autonomy of the Bulgarian church after centuries of Greek domination. This was a crucial step towards political independence, as the church became a unifying national institution.

The cultural revival inevitably fueled a desire for political freedom. A revolutionary movement began to take shape, inspired by ideals of liberty and self-determination sweeping across Europe. Its greatest ideologue and organizer was Vasil Levski, a brilliant and selfless strategist who envisioned a "pure and sacred republic" for all its citizens, regardless of ethnicity or religion. His capture and execution by the Ottomans in 1873 made him a national martyr and fanned the flames of rebellion. In April 1876, a poorly organized but fiercely courageous uprising, known as the April Uprising, broke out. The Ottoman response was swift and brutal, with massacres of thousands of innocent civilians, most famously in the town of Batak. The reports of these "Bulgarian Horrors" shocked Europe and galvanized public opinion, particularly in Russia, which saw itself as the protector of the Orthodox Slavs. In 1877, Russia declared war on the Ottoman Empire. The ensuing Russo-Turkish War saw Bulgarian volunteer forces fight heroically alongside Russian troops in pivotal battles, most notably at the Shipka Pass. The Russian victory led to the signing of the Treaty of San Stefano on March 3, 1878, which created a large, autonomous Bulgarian state.

The creation of modern Bulgaria, however, was immediately complicated by the ambitions of Europe's Great Powers. Wary of a large Russian client state in the Balkans, they convened the Congress of Berlin just a few months later. The resulting Treaty of Berlin drastically revised the San Stefano agreement, carving the new Bulgaria into three parts: a smaller, semi-independent Principality of Bulgaria, an autonomous Ottoman province of Eastern Rumelia, and large territories in Macedonia and Thrace that were returned to direct Ottoman rule. This division was a bitter disappointment and would fuel Bulgarian foreign policy for decades to come, leading to a series of national irredentist struggles. Despite this setback, the Third Bulgarian State was born. In 1885, a bloodless unification with Eastern Rumelia was achieved, a bold act of defiance against the Great Powers. The early decades of the new state were tumultuous, marked by the reign of its first prince, Alexander of Battenberg, political intrigue, and wars against its neighbors, but the foundations of a modern nation were laid.

The 20th century would prove to be one of the most violent and disruptive periods in Bulgaria's long history. Driven by the desire to unite all lands with a majority Bulgarian population, the country plunged into the Balkan Wars of 1912-1913. While initially successful, disputes with its allies led to a disastrous Second Balkan War that resulted in territorial losses. This sense of national grievance pushed Bulgaria to side with the Central Powers in World War I, hoping to reclaim what it had lost. The defeat in 1918 was another national catastrophe, leading to further loss of territory and a heavy burden of reparations. The interwar years were characterized by political instability, military coups, and social unrest. In World War II, Bulgaria, under Tsar Boris III, allied itself with Nazi Germany to achieve its territorial ambitions in the Balkans, but famously resisted German pressure to deport its Jewish population. As the tide of the war turned, the Soviet Union declared war on Bulgaria, and in September 1944, a Communist-led coup took place as Soviet forces entered the country.

The end of the war ushered in a new era. The monarchy was abolished, and the People's Republic of Bulgaria was established, becoming a loyal satellite of the Soviet Union within the Eastern Bloc. For the next 45 years, the country was ruled by the Bulgarian Communist Party, a period dominated by the long tenure of Todor Zhivkov, who was in power from 1954 to 1989. This era saw rapid industrialization and urbanization, but at the cost of political freedoms, dissent was suppressed, and the economy was centrally planned. The late 1980s were marked by economic stagnation and a controversial and repressive assimilation campaign against the country's ethnic Turkish minority. The winds of change sweeping across Eastern Europe in 1989 finally reached Bulgaria. On November 10, 1989, just one day after the fall of the Berlin Wall, Todor Zhivkov was removed from power in an internal party coup.

This event marked the beginning of Bulgaria's difficult and often painful transition to democracy and a market economy. The years that followed were a "time of troubles," with economic hardship, political uncertainty, and social dislocation. Yet, the transition remained peaceful. The country adopted a new democratic constitution in 1991, and a multi-party system took root. Slowly but surely, Bulgaria began to reorient itself towards the West. Having shed its Cold War alliances, the nation embarked on a new strategic path. This journey reached two major milestones in the 21st century: in 2004, Bulgaria became a member of NATO, anchoring its security in the Euro-Atlantic alliance, and in 2007, it joined the European Union, officially becoming part of the community of European democracies.

Today, Bulgaria stands as a nation that has come full circle. From the ancient Thracians to the Slavic migrations and the arrival of the Bulgars; from the rise of two glorious medieval empires to five centuries of Ottoman rule; from a dramatic national revival to the turbulent struggles of the 20th century and the embrace of a democratic European future, its history is a testament to survival and resilience. It is a story rich with cultural achievement, marked by profound tragedy, and defined by an unyielding spirit. This book will explore that story in all its complexity, nuance, and drama, seeking to understand the forces that have shaped this remarkable nation at the crossroads of history.

Before the name "Bulgaria" existed, the lands it now occupies were home to a remarkable and mysterious people known to antiquity as the Thracians. An Indo-European people who had settled in the southeastern Balkans by the second millennium BC, the Thracians were not a single, unified nation but a constellation of more than forty distinct tribes. Their territory was vast, stretching from the Carpathian Mountains in the north to the Aegean Sea in the south, and from the Vardar and Morava valleys in the west to the shores of the Black Sea in the east. The heartland of this ancient people, however, lay squarely within the territory of modern Bulgaria, defined by the Haemus (Balkan) Mountains and the fertile plains watered by the Hebrus (Maritsa), Strymon (Struma), and Nestos (Mesta) rivers.

Greek writers, from Homer onwards, portrayed the Thracians as a paradoxical people: fierce, red-haired warriors who fought with frenzied courage, yet also gifted musicians and creators of stunningly beautiful objects. They were renowned horse breeders, and their cavalry was both feared and respected in the ancient world. Society was fundamentally tribal, ruled by a warrior aristocracy whose wealth was measured in land, livestock, and spectacularly wrought gold and silver. These chieftains and kings were buried in monumental tombs, known as tumuli, filled with treasures that speak to a sophisticated culture with a profound appreciation for artistry and a complex understanding of the afterlife. These burial mounds, which still dot the Bulgarian landscape, particularly in the area that has become known as the "Valley of the Thracian Kings," have yielded some of the most breathtaking archaeological discoveries of the 20th century.

Thracian religion was a complex tapestry of chthonic deities, solar cults, and beliefs centered on the cycle of death and rebirth. The figure of Orpheus, the mythical singer whose music could charm wild beasts and even the gods of the underworld, is of Thracian origin. This hints at a powerful mystical tradition, often referred to as Orphism, which held that the soul was divine and immortal, trapped in a cycle of reincarnation from which it could escape through ritual purity and esoteric knowledge. Another key deity was Zalmoxis, worshipped particularly by the Getae tribe, who was believed to be an immortal god-man to whom believers would journey after death. The Thracians did not build grand stone temples in the Greek or Roman style; their sacred sites were often natural places of power—mountain peaks, caves, and groves—where they performed animal sacrifices and other rituals to honour their gods.

For centuries, the Thracian tribes existed in a state of flux, sometimes warring with one another, sometimes forming temporary alliances. Their lack of political unity made them vulnerable to outside powers. In the late 6th century BC, the mighty Persian Empire under Darius I expanded into Europe, subjugating many of the southern Thracian tribes and incorporating them into his vast domain. This period of Persian domination was relatively brief, however. The failure of the Persian invasions of Greece in the early 5th century BC created a power vacuum in the Balkans. It was in this environment that the first and most powerful Thracian state emerged.

Around 460 BC, a chieftain of the Odrysian tribe named Teres I managed, through a combination of warfare and diplomacy, to unite many of the disparate Thracian tribes into a single, formidable kingdom. The Odrysian Kingdom, at its height, controlled a vast territory encompassing most of modern-day Bulgaria, European Turkey, and northern Greece. Teres and his son, Sitalces, pursued an aggressive policy of expansion, creating one of the most powerful states of its time. Sitalces, in particular, became a significant player in the politics of the Greek world, forging an alliance with Athens during the Peloponnesian War and leading a massive army on a campaign into Macedonia. The wealth and power of the Odrysian kings were legendary, derived from taxes and tribute paid by the numerous tribes under their control, as well as from the lucrative trade that flowed through their lands.

While the Thracians dominated the interior, the coast of the Black Sea, or Pontus Euxinus ("Hospitable Sea") as the Greeks called it, was being transformed by the arrival of another people. Beginning in the 7th century BC, driven by land shortages and the lure of trade, Greek colonists began to establish city-states along the western shore of the Black Sea. Most of these settlers came from the great Ionian city of Miletus in Asia Minor. In 610 BC, they founded Apollonia Pontica (modern-day Sozopol), which would become one of the most ancient and prosperous cities in the region. Not long after, around the year 570 BC, another colony, Odessos (modern-day Varna), was established on the site of an earlier Thracian settlement. Another major settlement, Mesembria (modern-day Nesebar), was founded on a rocky peninsula by Dorian Greeks from Megara in the 6th century BC.

These Greek cities were fiercely independent poleis, bringing with them their language, religion, architecture, and democratic traditions. They were essentially islands of Hellenic culture on the edge of a "barbarian" sea. Their relationship with the Thracian tribes of the hinterland was complex and symbiotic. It was a relationship built on trade; the Greeks exchanged luxury goods, wine, and pottery for Thracian grain, timber, leather, and, most importantly, metals like gold and copper. This interaction led to a fascinating cultural fusion. Thracian aristocrats adopted Greek styles and customs, while Greek art began to incorporate Thracian motifs. However, the relationship was not always peaceful. The cities had to build strong fortification walls to protect themselves from raids, and conflicts over territory and resources were common.

The delicate balance of power in the region was shattered in the mid-4th century BC with the rise of a new force to the southwest: the kingdom of Macedon. King Philip II, a brilliant military strategist and diplomat, saw Thrace as a vital source of resources and a strategic gateway to the east. In a series of campaigns between 356 and 340 BC, Philip systematically conquered the Thracian lands, defeating their tribes and subjugating the once-mighty Odrysian kingdom, which had by then fractured into several smaller states. He founded new cities, most notably Philippopolis (modern-day Plovdiv), in the heart of the Thracian plain, settling them with Macedonians to secure his control. The Greek cities on the coast were also brought under Macedonian influence, losing their cherished independence.

Philip's son, Alexander the Great, continued his father's work, crushing a Thracian revolt early in his reign before embarking on his legendary conquest of the Persian Empire. After Alexander's death in 323 BC, his vast empire was torn apart by his generals, the Diadochi, in a series of wars. Thrace became the domain of Lysimachus, who proclaimed himself king and even established his capital there for a time. This period, known as the Hellenistic Age, saw a deepening of Greek cultural influence in the region. However, Thracian resistance never fully died out. A revived, smaller Odrysian state under King Seuthes III even managed to re-establish a measure of independence, founding a new capital, Seuthopolis, in the late 4th century BC. The subsequent centuries were a period of instability, marked by the disruptive invasion of Celtic tribes in the 3rd century BC and the constant shifting of power between local Thracian rulers.

By the 2nd century BC, a new and inexorable power was making its presence felt in the Balkans: Rome. The Roman Republic's expansion eastward brought it into conflict first with Macedon and then with the various tribes of the Balkan peninsula. The process of conquering the Thracian lands was a long, brutal, and piecemeal affair, lasting for more than a century. The Romans fought a series of grueling campaigns against the fiercely independent Thracian tribes, who used their knowledge of the mountainous terrain to wage effective guerrilla warfare. Rebellions were frequent and savagely suppressed.

The final subjugation of the region began in earnest in the 1st century BC. A campaign by Marcus Licinius Crassus in 28 BC established Roman control over the northern regions along the Danube River. The southern Thracian lands were initially allowed to continue as a Roman client kingdom under the rule of the Odrysian dynasty. This arrangement, however, was a prelude to full annexation. After the murder of the last Thracian client king, Rhoemetalces III, the Emperor Claudius formally annexed the kingdom in 46 AD, creating the Roman province of Thracia. The lands to the north of the Balkan Mountains had already been organized into the province of Moesia around 15 AD. Later, during the reign of Emperor Domitian in the 80s AD, Moesia was divided into two provinces: Moesia Superior and Moesia Inferior.

With the imposition of the Pax Romana, the "Roman Peace," life in these new provinces was fundamentally transformed. The Romans were master engineers and administrators. They built an extensive network of roads, connecting the Danube frontier with the Aegean Sea and facilitating the movement of troops and trade. Great cities rose, some on the sites of older Thracian settlements. Serdica (modern-day Sofia), Philippopolis (Plovdiv), and Odessos (Varna) were expanded and adorned with the hallmarks of Roman urban life: forums, temples, theaters, and public baths. Latin became the language of administration and the military, particularly in Moesia, while Greek remained dominant in the more Hellenized province of Thracia.

Roman rule brought economic prosperity to the region. The fertile plains of Moesia and Thrace became important sources of grain for the empire. Mining for gold, silver, and iron in the mountains was expanded and industrialized. Large agricultural estates, or villas, were established, often on land granted to retired Roman soldiers. Thracians themselves were heavily recruited into the Roman army, particularly as auxiliary cavalry, their renowned martial skills now serving the empire that had conquered them. Over time, the local aristocracy became Romanized, adopting Roman names, customs, and the toga, and participating in the governance of their cities. Yet, beneath this veneer of Roman civilization, local Thracian culture and language persisted, especially in the rural areas.

Along with Roman roads and legions came new ideas and beliefs. The multicultural environment of the Roman Empire was fertile ground for the spread of new religions, and by the 2nd and 3rd centuries AD, Christianity began to take root in the cities of Thrace and Moesia. Initially a faith practiced in secret by small communities, it gradually grew in influence, despite periods of persecution. The strategic importance of the region is highlighted by the fact that in 343 AD, a major church council was held in Serdica (Sofia). Convened by the emperors Constans and Constantius II, the Council of Serdica attempted, unsuccessfully, to heal the growing rift between the eastern and western branches of the church over the Arian controversy.

The mid-3rd century AD marked the beginning of a long period of crisis for the Roman Empire. The imperial system was strained by civil wars, economic turmoil, and, most pressingly for the Balkan provinces, intense and unrelenting pressure on its frontiers. The Danube, once a clear line of demarcation, became increasingly porous. Waves of "barbarian" peoples—Goths, Carpians, and others—began to launch devastating raids deep into Moesia and Thrace, sacking cities and disrupting life. The emperor Decius was even killed in battle against the Goths at Abritus in Moesia in 251 AD. The province of Dacia, across the Danube, was abandoned in the 270s, placing even more pressure on the Balkan provinces.

The final decades of the 4th century brought a cataclysmic series of events that would irrevocably change the region. In 376 AD, vast numbers of Goths, refugees fleeing the advance of the Huns from the east, sought asylum within the Roman Empire. They were allowed to cross the Danube into Moesia, but corruption and mistreatment by Roman officials soon led to a massive and desperate rebellion. The ensuing Gothic War ravaged the Balkans. The crisis reached its devastating climax on August 9, 378, near the city of Adrianople (modern-day Edirne) in Thrace. A large Eastern Roman army, led by the Emperor Valens himself, rashly engaged the combined Gothic forces. The result was an unmitigated disaster for Rome. The Roman army was annihilated, and Emperor Valens was killed. The Battle of Adrianople was a shattering blow from which the empire would never fully recover. It exposed the vulnerability of the Roman frontier, left the Balkan provinces defenseless, and set the stage for the great migrations of peoples that would reshape the map of Europe and lay the foundations for a new historical era.