The arrival of Germanic-speaking invaders along the coast of the Black Sea is generally explained as a gradual migration of the Goths from what is now Poland to Ukraine, reflecting the tradition of Jordanes and old songs.

The Goths—Germans coming from what is now Sweden—will be followed by the Vandals, the Burgundians, and the Gepidae.

The aftereffect of their march to the southeast, toward the Black Sea, had been to push the Marcomanni, the Quadi, and the Sarmatians onto the Roman limes in Marcus Aurelius' time.

Their presence is brusquely revealed to the civilized Greco-Roman world when they attack the Greek towns on the Black Sea about 238.

The Burgundians (Latin: Burgundiones), an East Germanic tribe, may have emigrated from mainland Scandinavia to the island of Bornholm, whose old form in Old Norse still was Burgundarholmr (the Island of the Burgundians), and from there to mainland Europe.

The Burgundians' tradition of Scandinavian origin finds support in place-name evidence and archaeological evidence (Stjerna) and many consider their tradition to be correct (e.g., Musset, p. 62).

Possibly because Scandinavia was beyond the horizon of the earliest Roman sources, including Tacitus (who only mentions one Scandinavian tribe, the Suiones), Roman sources do not mention where the Burgundians came from, and the first Roman references place them east of the Rhine (inter alia, Ammianus Marcellinus, XVIII, 2, 15).

Early Roman sources consider them simply another East Germanic tribe.

The population of Bornholm (the island of the Burgundians) in about 250 largely disappears from the island.

Most cemeteries cease to be used, and those that are still used have few burials (Stjerna, in Nerman 1925:176).

A coalition of Alamanni, Burgundians, and Franks, scarcely opposed, had crossed the Rhine in 256 and overrun Gaul; elements of the two super-tribes reach as far as Italy and Spain.

The Franks, the Longiones, and the Vandals, despite their huge numbers, have all been defeated within two years.

At one point, Probus had captured the leader of the Longiones, called Semnon, and upon Semnon's acceptance of terms permitted his return to his homeland with his surviving people.

At one occasion during these successful campaigns, sixteen German chiefs are said to have knelt at Probus' feet.

Hostages are taken to ensure the peace and some sixteen thousand Germans are recruited into the Roman army.

In 279, the emperor sets out for Syria, desiring to reconquer Mesopotamia from Sassanid Persia.

Bagaudae (also spelled bacaudae) are groups of peasant insurgents who emerge during the "Crisis of the Third Century", and persist particularly in the less Romanized areas of Gaul and Hispania.

The name probably means "fighters".

C.E.V. Nixon assesses the bagaudae, from the official Imperial viewpoint, as "bands of brigands who roamed the countryside looting and pillaging."

J.C.S. Léon interprets the most completely assembled documentation as identifying the bagaudae as the impoverished local free peasants, reinforced by bandits and deserters from the legions, who are resisting the extension of proto-feudal privileges and control in marginal areas of the Empire.

Léon sees the invasions, usurpers and disorders of the third century crisis not as causative, but as providing a chaotic relaxation of local power, within which the bagaudae achieve some temporary and scattered successes, under the leadership of lesser members of the ruling class.

The bagaudae first come to the attention of the central authorities in 285.

The fourth-century historian Eutropius describes them as rural people under the leadership of Amandus and Aelianus, while Aurelius Victor called them bandits.

The historian David S. Potter suggests that they were more than peasants, seeking either Gallic political autonomy or reinstatement of the recently deposed Carus (a native of Gallia Narbonensis, in what would become southern France): in this case, they would be defecting imperial troops, not brigands.

Although poorly equipped, led and trained—and therefore a poor match for Roman legions—Diocletian certainly considered bagaudae a threat sufficient to merit an emperor to counter them.

E.M. Wightman, in Gallia Belgica, claims that Amandus and Aelianus were likely local Gallic landowners who became "tyrants" and fought back against the Romans.

The Panegyric of Maximian, dating to 289 and attributed to Claudius Mamertinus, relates that during the bagaudae uprising of 284–285, "inexperienced farmers sought military garb; the plowman imitated the infantryman, the shepherd the cavalryman, the rustic ravager of his own crops the barbarian enemy".

In fact, they share several similar characteristics with the Germanic Heruli.

Mamertinus also called them "two-shaped monsters" (monstrorum biformium), emphasizing that while they were technically Gallo-Roman farmers and citizens, they were also marauding rogues who had become foes of the empire.

Maximian travels to Gaul late in the summer of 285, engaging the Bagaudae.

Details of the campaign are sparse and provide no tactical detail: the historical sources dwell only on Maximian's virtues and victories.

The 289 panegyric to Maximian records that the rebels were defeated with a blend of harshness and leniency.

As the campaign was against the Empire's own citizens, and therefore distasteful, it went unrecorded in titles and official triumphs.

Indeed, Maximian's panegyrist declares: "I pass quickly over this episode, for I see in your magnanimity you would rather forget this victory than celebrate it." (Panegyrici Latini 10(2), quoted in Williams, 46; Southern, 137.)

The revolt has significantly abated by the end of the year, and Maximian moves the bulk of his forces to the Rhine frontier, heralding a period of stability.

Maximian had not put down the Bagaudae swiftly enough to avoid a Germanic reaction.

Two barbarian armies—one of Burgundians and Alamanni, the other of Chaibones and Heruli—ford the Rhine in the autumn of 285 and enter Gaul.

The first army is left to die of disease and hunger, while Maximian intercepts and defeats the second.

He then establishes a Rhine headquarters in preparation for future campaigns, either at Moguntiacum (Mainz, Germany), …

…Augusta Treverorum (Trier, Germany), or …

…Colonia Agrippina (Cologne, Germany).

The western extent of modern-day Switzerland is part of the territory of the Kings of the Burgundians from the end of the fourth century.

The Alemanni settle the Swiss plateau in the fifth century and will settle the valleys of the Alps in the eighth century, forming Alemannia.

Modern-day Switzerland is therefore then divided between the kingdoms of Alemannia and Burgundy.

The entire region becomes part of the expanding Frankish Empire in the sixth century, following Clovis I's victory over the Alemanni at Tolbiac in 504, and later Frankish domination of the Burgundians.

Mediterranean West Europe (388–531 CE): Decline of Roman Authority, Barbarian Settlements, and Religious Consolidation

Between 388 and 531 CE, Mediterranean West Europe—comprising southern France (below an imaginary line from approximately 43.03476° N, 1.17208° W to 46.45234° N, 6.07689° E), Corsica, and Monaco—undergoes substantial upheavals characterized by the decline of Roman imperial power, the influx and settlement of barbarian groups, and the deepening of Christian influence across the region.

Decline of Roman Imperial Control

As the Western Roman Empire weakens, central authority begins to falter significantly throughout Mediterranean West Europe. Administrative inefficiency, economic disruptions, and the increasing burden of military expenses accelerate the erosion of Roman power. Local governance becomes increasingly autonomous, as provincial officials assume greater responsibilities to manage internal affairs independently of distant Rome.

Barbarian Invasions and Settlements

The period witnesses substantial incursions by various Germanic tribes, including the Visigoths and the Burgundians, who move into the region seeking new territories. In 412 CE, the Visigoths establish a significant presence in Aquitaine, and by the late fifth century, their kingdom encompasses much of southwestern France, influencing areas as far east as Provence. Meanwhile, Burgundian settlers establish themselves along the Rhône valley, significantly reshaping local societies and economies.

Socioeconomic Transformations

The integration of barbarian groups into local societies leads to profound socioeconomic changes. Rural areas increasingly rely on fortified villa complexes and self-sufficient communities to withstand the instability of the era. Urban centers, though reduced in economic prosperity compared to previous centuries, remain vital as administrative and religious hubs. Cities such as Arles, Massalia (Marseille), and Nemausus (Nîmes) continue to serve as important cultural and economic centers, albeit under shifting political authorities.

Consolidation and Expansion of Christianity

Christianity deepens its influence during this era, with the church becoming a central pillar of regional stability and continuity amid political turmoil. Bishops and monastic leaders, notably figures such as Caesarius of Arles, play crucial roles in maintaining social order, offering spiritual leadership, and providing charity and education. Monasticism expands significantly, with numerous monasteries founded across southern France and Corsica, further embedding Christian values and practices within local communities.

Cultural Adaptation and Fusion

Culturally, the region experiences a blending of Roman traditions with the customs and practices of incoming barbarian groups. Latin remains the dominant language, facilitating continuity in administrative, legal, and religious practices. However, new Germanic cultural elements integrate with Roman traditions, creating unique hybrid identities. Christian festivals increasingly supplant traditional Roman pagan celebrations, reinforcing the centrality of Christian rituals and symbols in everyday life.

Prelude to Early Medieval Stability

By 531 CE, Mediterranean West Europe transitions into the Early Middle Ages, having navigated a complex period marked by declining Roman imperial authority, significant population shifts due to barbarian settlements, and the definitive establishment of Christianity as the region’s dominant cultural force. These transformations lay the groundwork for the medieval societies that will characterize the region in subsequent centuries, emphasizing localized governance, Christian religious dominance, and the continued blending of diverse cultural traditions.