The Migration Period (c. 300–700 CE): The Transition from Late Antiquity to the Early Middle Ages

The Migration Period, also known as the Völkerwanderung ("wandering of peoples"), was a major human migration that took place in Europe between roughly 300 and 700 CE, marking the transition from Late Antiquity to the Early Middle Ages. From the Roman and Greek perspective, it is often referred to as the "Barbarian Invasions."

Causes of the Migration

Several factors contributed to the mass movement of peoples across Europe:

1. The Hunnic Incursions (4th–5th centuries)

   • The Huns, a nomadic people possibly of Turkic or Mongolic origin, swept into Eastern Europe from Central Asia.
   • Their advance forced Germanic and other tribes to flee westward, triggering further migrations.

2. Turkic and Steppe Migrations

   • The early Turkic expansion and shifting power dynamics in Central Asia contributed to displacements among nomadic groups.

3. Population Pressures and Climate Change

   • Environmental changes and resource depletion in certain regions may have compelled migrations.
   • Overpopulation or crop failures in northern Europe might have prompted tribes to seek new lands.

Key Migratory Groups and Their Impact

• Goths – Split into Visigoths and Ostrogoths, they played key roles in the fall of the Western Roman Empire.
• Vandals – Migrated through Gaul and Spain, eventually sacking Rome in 455 CE before establishing a kingdom in North Africa.
• Suebi – Settled in northwestern Iberia, forming the Kingdom of Galicia (modern Portugal and Spain).
• Franks – Established the Frankish Kingdom, which evolved into modern France and Germany.
• Bulgars, Slavs, and Alans – Entered the Balkans and Eastern Europe, reshaping its ethnic and linguistic landscape.

Continuation of Migrations Beyond 700 CE

Migrations did not stop in 700 CE; instead, successive waves of nomadic and Slavic peoples continued reshaping Europe:

• Slavs – Expanded across Central and Eastern Europe, influencing later Slavic nations.
• Avars, Bulgars, and Hungarians – Established powerful steppe empires in Eastern Europe.
• Pechenegs, Cumans, and Tatars – Continued nomadic invasions into Byzantium and Kievan Rus’ in the medieval period.

Significance of the Migration Period

• Led to the decline of the Western Roman Empire (476 CE) and the foundation of early medieval European kingdoms.
• Marked the cultural and linguistic transformation of Europe, laying the groundwork for medieval political structures.
• Accelerated the fusion of Roman, Germanic, and steppe influences, which defined the social, legal, and economic systems of medieval Europe.

The Migration Period was a defining era in European history, setting the stage for feudal societies, the rise of new kingdoms, and the shaping of modern European nations.

Eastern Southeast Europe (388–531 CE): Transition, Division, and Byzantine Emergence

Settlement and Migration Patterns

Barbarian Invasions and Settlements

Between 388 and 531 CE, Eastern Southeast Europe experienced extensive migrations and invasions from groups including the Huns, Alans, Antes, Gepids, Visigoths, Ostrogoths, Iazyges, and later the Avars and Kutrigurs (Bulgars). These movements significantly affected regional stability, settlement patterns, and demographic composition. In 448, the Huns ravaged key cities such as Sirmium (modern-day Sremska Mitrovica), Singidunum (Belgrade), and Emona (Ljubljana). By 493, the Ostrogoths had established dominance over Dalmatia and other provinces, though later driven out by Emperor Justinian I in the sixth century.

Roman Provincial Reorganization

Significant Roman provincial reorganizations occurred, establishing provinces such as Pannonia Savia, Pannonia Secunda, Pannonia Valeria (modern Slavonia, Vojvodina, and the Banat), Moesia Prima, Moesia Secunda, Dacia Ripensis, Scythia Minor, and Europa. These administrative divisions enhanced governance, security, and economic integration.

Urban Adaptation and Transformation

Cities adapted through improved fortifications. Byzantium, renamed Constantinople by Emperor Constantine in 330 CE, emerged prominently as the Byzantine capital. After the catastrophic Battle of Adrianople (378), where the Visigoths defeated Emperor Valens, Constantinople's defenses were greatly enhanced. Theodosius II constructed the city's formidable eighteen-meter-tall triple-wall fortifications, impenetrable until the advent of gunpowder.

Economic and Technological Developments

Economic Realignment and Resilience

Despite disruptions from migrations and warfare, regional economies adapted effectively. Constantinople became a major economic hub, facilitating commerce between Europe, Asia Minor, and the broader Mediterranean. Wealth from the eastern Mediterranean and western Asia flowed into the city, establishing it as the largest urban center following the Western Roman Empire's fall.

Military and Defensive Innovations

Technological advancements emphasized defensive infrastructure, including enhanced fortifications, improved military equipment, and sophisticated logistics, sustaining military effectiveness amidst external threats and securing strategic locations.

Cultural and Artistic Developments

Byzantine Cultural Flourishing

Constantinople and major cities experienced a cultural renaissance, exemplified by sophisticated architecture, mosaics, and public art reflecting imperial grandeur and Christian spirituality. The founding of a university near the Forum of Taurus in 425 by Theodosius II exemplified significant cultural and intellectual investments.

Preservation of Classical Heritage

Classical Greek and Roman knowledge was preserved through educational institutions and libraries, ensuring continued influence of classical texts, philosophies, and scientific knowledge in regional education and culture.

Social and Religious Developments

Evolution of Byzantine Governance

Roman provincial governance evolved into the distinctive Byzantine administrative system with centralized bureaucracy and complex provincial structures. The division of the Roman Empire in 395 by Emperor Theodosius's sons permanently separated Greek-speaking Constantinople from Latin Rome, profoundly influencing cultural and political dynamics, especially among future Serbs and Croats.

Christianity’s Ascendancy and Theological Debates

Christianity became deeply intertwined with political authority and cultural identity. Theological debates surrounding Arianism and Christological doctrines significantly influenced religious practices and social dynamics. Constantinople established a patriarchate exercising ecclesiastical jurisdiction over much of the Greek East, reinforcing Christianity's regional prominence.

Long-Term Consequences and Historical Significance

The period from 388 to 531 CE was transformative, transitioning Eastern Southeast Europe from late Roman territories into the Byzantine Empire. Demographic shifts, economic realignments, cultural flourishing, and religious developments laid the foundations of Byzantine civilization, significantly shaping the region’s historical trajectory.

The Weakening of Roman Power and the Rise of the Franks in the Low Countries

By the mid-third century, Roman control in the Low Countries had begun to deteriorate. The abandonment of forts and military outposts was driven not only by the resurgence of Germanic tribes but also by environmental changes, as the encroaching sea likely disrupted regional economies and settlements. This combination of external pressures and economic decline accelerated the fragmentation of Roman authority.

A temporary recovery took shape by the late third century, as Rome sought to reassert control. One of the most significant efforts came under Julian, Caesar of Gaul, who between 355 and 360 CE waged several military campaigns in the Low Countries, briefly restoring strength to the Rhine frontier.

The Dual Role of the Franks: Raiders and Defenders

Despite these efforts, Frankish incursions into Roman territory continued. While some Franks raided Roman lands, others integrated into the imperial military, forming a complex and shifting relationship with Roman authorities.

• Major Roman armies remained positioned 100 miles (160 km) south and west of the Rhine River Valley, securing the frontier.
• Meanwhile, Frankish settlers occupied lands north and east of Roman strongholds, acting as a buffer state and providing intelligence to Roman commanders.

By the mid-fourth century, Frankish soldiers had risen to prominence within the Roman army, with figures such as Magnentius, Silvanus, and Arbitio wielding significant power. The historian Ammianus Marcellinus describes how both Frankish and Alamannic forces had adopted Roman military structures and tactics, making them formidable opponents—and, at times, valuable allies.

The Salian Franks and Their Foederati Status

A pivotal moment came in 358 CE, when Julian formalized an arrangement with the Salian Franks, allowing them to settle in northern Gaul—lands that had been depopulated over the previous century. In return, the Salian Franks became foederati (federated allies), obligated to defend Roman interests in the region.

This marked the beginning of a longer-term Frankish presence within Roman Gaul. Over time, their influence would grow, setting the stage for their eventual ascendancy as rulers of post-Roman Gaul, culminating in the reign of Clovis I and the foundation of the Frankish kingdom.

Basiliscus, likely of Balkan origin, is the brother of Aelia Verina, wife of Leo I.

It has been argued that Basiliscus was uncle to the chieftain of the Heruli, Odoacer.

This link is based on the interpretation of a fragment by John of Antioch (209.1), which states that Odoacer and Armatus, Basiliscus' nephew, were brothers.

However, not all scholars accept this interpretation, since sources do not say anything about the foreign origin of Basiliscus.

It is known that Basiliscus had a wife, Zenonis, and at least one son, Marcus.

Basiliscus' military career had started under Leo I, when the Emperor conferred upon his brother-in-law the dignities of dux, or commander-in-chief, in Thrace.

In this country, Basiliscus had led a successful military campaign against the Bulgars in 463.

Succeeding Rusticius as magister militum per Thracias in 464, he had had several successes against the Goths and Huns (466 or 467).

Basiliscus's value had risen in Leo's consideration.

Verina's intercession in favor of her brother has helped Basiliscus' military and political career, with the conferral of the consulship in 465 and possibly of the rank of patricius.

However, his rise is soon to meet a serious reversal.

In 468, Leo chooses Basiliscus as leader of the later famous military expedition against Carthage.

The invasion of the kingdom of the Vandals is one of the greatest military undertakings recorded in the annals of history, a combined amphibious operation with over ten thousand ships and one hundred thousand soldiers.

The purpose of the operation is to punish the Vandal king Genseric for the sacking of Rome in 455, in which the former capital of the Western Roman Empire had been overwhelmed, and the Empress Licinia Eudoxia (widow of Emperor Valentinian III) and her daughters had been taken as hostages.

Ancient and modern historians provide different estimations for the number of ships and troops under the command of Basiliscus, as well as for the expenses of the expedition.

Both are enormous; Nicephorus Gregoras speaks of one hundred thousand ships, the more reliable Cedrenus says that the fleet that attacked Carthage consisted of eleven hundred and thirteen ships, having each one hundred men on board.

The most conservative estimation for expedition expenses is of sixty-four thousand pounds of gold, a sum that exceeds a whole year's revenue.

It is the greatest fleet ever sent against the Vandals; the expense brings Leo near to bankruptcy.

Marcellinus was supposed to have a command of some ten thousand to twenty thousand troops.

Marcellinus had never sailed for Africa, perhaps due to Ricimer's veto; either he would not spare so many troops to become bogged in a campaign in Africa, hoping the East would do the job for him, or he resented the military capabilities of Marcellinus who was obviously the favorite of Anthemius.

Regardless of the reason, Marcellinus’s inabiity to participate in the campaign, coupled with Basiliscus’s blundering in the Battle of Cape Bon, assured that the operation would result in failure.

The West has lost its only chance to regain Africa from the Vandals and possibly stave off its demise.

Marcellinus is reached in Sicily by Basiliscus; the general is, however, assassinated, perhaps at the instigation of Ricimer, by one of his own captains; and the king of the Vandals expresses his surprise and satisfaction that the Romans themselves would remove from the world his most formidable antagonists.

The Vandals reconquer Sicily, administering a decisive defeat to the Western forces.

The Roman plan of attack is concerted between Eastern Emperor Leo, Western Emperor Anthemius, and General Marcellinus, who enjoys independence in Illyricum.

Basiliscus is ordered to sail directly to Carthage, while Marcellinus attacks and takes Sardinia, and a third army, commanded by Heraclius of Edessa, lands on the Libyan coast east of Carthage, making rapid progress.

It appears that the combined forces met in Sicily, whence the three fleets moved at different periods.

Sardinia and Libya have already been conquered by Marcellinus and Heraclius, when Basiliscus casts anchor off the Promontorium Mercurii, now Cap Bon, opposite Sicily, about forty miles from Carthage.

Genseric requests Basiliscus to allow him five days to draw up the conditions of a peace.

During the negotiations, Geiseric gathers his ships and suddenly attacks the Roman fleet.

The Vandals had filled many vessels with combustible materials.

During the night, these fire ships are propelled against the unguarded and unsuspecting Roman fleet.

The Eastern Roman commanders try to rescue some ships from destruction, but these maneuvers are blocked by the attack of other Vandal vessels.

Basiliscus flees in the heat of the battle.

One half of the Roman fleet is burned, sunk, or captured, and the other half follow the fugitive Basiliscus.

The entire expedition has failed.

Heraclius effects his retreat through the desert into Tripolitania, where he will hold the position for two years until recalled.

The origin of the early Bulgars (or "Proto-Bulgars") is still unclear.

Their homeland is believed to be situated in Kazakhstan and the North Caucasian steppes.

Interaction with the Hunnic tribes, causing the migration, may have occurred there, but the Pontic–Caspian steppe seems a more likely location.

The first clear mention and evidence of the Bulgars is in the 480s, when they serve as the allies of the Byzantine Emperor Zeno (474–491) against the Ostrogoths.

According D. Dimitrov, the fifth century History of Armenia by Movses Khorenatsi speaks about two migrations of the Bulgars, from Caucasia to Armenia.

The first migration is mentioned in the association with the campaign of Armenian ruler Valarshak (probably Varazdat) to the lands "named Basen by the ancients... and which were afterwards populated by immigrants of the vh' ndur Bulgar Vund, after whose name they (the lands) were named Vanand".

The second migration took place during the time of the ruler Arshak III, when "great disturbances occurred in the range of the great Caucasus mountain, in the land of the Bulgars, many of whom migrated and came to our lands and settled south of Kokh".

Both migrations are dated to the second half of the fourth century.

The "disturbances" that caused them are believed to be the expansion of the Huns in the East-European steppes.

Dimitrov recorded that the toponyms of the Bolha and Vorotan rivers, tributaries of the Aras river, are known as Bolgaru-chaj and Vanand-chaj, and could confirm the Bulgar settlement of Armenia.

The Akatziroi and other tribes that had been part of the Hunnic union were attacked around 463, tby the Šarağurs, one of the first Oğuric Turkic tribes that entered the Ponto-Caspian steppes as the result of migrations set off in Inner Asia.

According to Priscus, in 463 the representatives of Šarağur, Oğur and Onoğur came to the Emperor in Constantinople, and explained they had been driven out of their homeland by the Sabirs, who had been attacked by the Avars.

This tangle of events indicates that the Oğuric tribes are related to the Dingling and Tiele people.

It seems that Kutrigurs and Unigurs arrived with the initial waves of Oğuric peoples entering the Pontic steppes.

The Bulgars were not mentioned in 463.

The eighth-century account by Paul the Deacon in his History of the Lombards says that at the beginning of the fifth century in the northwestern slopes of the Carpathians the Vulgares killed the Lombards’ king Agelmund.

Scholars attribute this account to the Huns; Avars or some Bulgar groups were probably carried away by the Huns to the Central Europe.

When the army of Ostrogoth chieftain Theodoric Strabo grows to thirty-thousand-men strong, it is felt as a menace to Emperor Zeno, who somehow manages to persuade the Bulgars to attack the Thracian Goths.

The Bulgars are in 480/481 defeated, however, by Strabo.

Theodoric Strabo defeats the Bulgars in Thrace and moves with an army (thirteen thousand men) towards Constantinople.

After logistical problems, he is forced to return to Greece.

In an encampment at Stabulum Diomedis, near Philippi, he falls from an unruly horse onto a spear and dies.

The movement of the Slavs from their original homeland north of the Carpathians to other parts of East Central Europe is apparently linked in large part to the invasion between the fifth and sixth centuries of nomadic peoples from the east.

The Huns, Alans, and Kutrigur Bulgars in turn subject certain Slavic tribes and often take them along on raids against the Eastern Roman Empire.

The Kutrigur Bulgars probably originated as a Turkic tribe of Central Asia and arrived in the European steppe west of the Volga River with the Huns about 370; retreating with the Huns, they resettled about 460 in an arc of country north and east of the Sea of Azov.

Hired by the East Romans in 480 to fight against the Ostrogoths, the Bulgars subsequently have attracted by the wealth of the empire.

From 493, the Bulgars continually attack the western Danubian provinces of the Empire.

Meanwhile, small Slavic groups have in the fifth century begun settling outlying regions in the region of what is today Bulgaria.

The Slavs, characteristically sedentary farming and livestock-raising tribes, speak an Indo-European language and organize themselves into clans ruled by a council of family chiefs, holding in common all land and significant wealth.