Between the sixth and the second centuries BCE, the Celtic-speaking peoples of Europe underwent one of the most dramatic expansions of any pre-industrial civilization. From a core homeland in the upper and middle Danube, the Rhine, and eastern France, Celtic tribes, war bands, and individual migrants spread westward into the British Isles, southward into the Iberian Peninsula and the Italian heartland, eastward into the Balkans, and ultimately southeastward into the plains of central Anatolia. To follow the Iron Age Celtic expansion is to witness the formation of the largest cultural and linguistic zone in pre-Roman Europe outside the Mediterranean itself, a transformation that set the stage for every subsequent chapter of the history of the Celtic civilization.
The expansion was not a single event but a long, complex, and uneven process. Different regions were affected at different times and in different ways. Some were settled by large tribal movements that established permanent Celtic-speaking populations. Others were reached by smaller war bands or by individual adventurers whose impact on the local culture was more limited. In some regions, the Celtic presence was so strong that it left a permanent mark on the language, the place names, and the material culture of the area. In others, the Celtic overlay was thin and was soon absorbed by the surrounding population. The story of the Celtic expansion is therefore not the story of a single migration but of many overlapping movements, each with its own dynamics and its own consequences.
The Celtic Heartland
At the beginning of the expansion, around 500 BCE, the core area of the Celtic world lay in the regions of modern eastern France, southern Germany, Switzerland, Austria, the Czech Republic, Slovakia, and Hungary. This is the area in which the Hallstatt and early La Tène cultures had developed and from which the distinctive La Tène art style was beginning to radiate. The major tribal groupings of this region, as they emerge in the historical record of the fourth and third centuries BCE, included the Boii in Bohemia (whose name survives in the modern placename Bohemia and in the later Bavaria and Bohème), the Volcae Tectosages in the upper Danube, the Helvetii in the Swiss plateau, the Sequani and Aedui in the Saône and upper Loire valleys, the Arverni in the Massif Central, and the Senones in the region around modern Sens in northern Burgundy.
The economy of this Celtic heartland was based on a mixture of agriculture, pastoralism, and metallurgy. The region was rich in iron, copper, tin, gold, and salt, and the working of these metals was a major source of wealth and a major stimulus to long-distance trade. The great salt-mining center of Hallstatt itself continued to be productive into the La Tène period, and the trade in salt, iron, and bronze brought Celtic goods and Celtic merchants to every part of the European continent.
The political structure of the Celtic heartland in the early La Tène period is poorly documented, but the rich burials of the period suggest a society organized around warrior aristocracies with control over extensive territories. The Vix burial in Burgundy, the Hochdorf princely grave in southwestern Germany, and the Magny-Lambert burial in the same region all attest to chiefs who could command the labor of hundreds of workers and the tribute of large regions. By the fourth century BCE, these aristocratic families had begun to coalesce into the larger tribal groupings that would dominate the political landscape of the Celtic world into the Roman period.
Expansion into the West: Gaul and the Atlantic
The earliest and most successful direction of Celtic expansion was westward, into Gaul and the Atlantic coast. By the beginning of the fourth century BCE, Celtic-speaking populations had spread across most of what is now France, replacing or absorbing the earlier Bronze Age populations and giving their names to many of the major rivers and regions: the Seine (Sequana), the Loire (Liger), the Garonne (Garumna), the Marne (Matrona), the Moselle (Mosella), and the Saône (Arar). The major tribal groupings of Gaul, including the Aedui, Arverni, Bituriges, Carnutes, Senones, Remi, and many others, were already established by the time of the Roman invasion in the mid-first century BCE, and Caesar counted more than sixty separate peoples in Gaul alone.
The expansion into the Atlantic coast and the British Isles is more difficult to trace, since the archaeological record is more sparse and the literary sources are later. It is clear, however, that Celtic-speaking populations had reached the Atlantic coast of France and the British Isles by the fourth or third century BCE, bringing with them the La Tène art style, the roundhouse, the iron sword, and the war chariot. The Goidelic Celtic languages, ancestors of modern Irish and Scottish Gaelic, appear to have been carried to the British Isles in this period, although the chronology of the various waves of migration is debated. The Brythonic Celtic languages, ancestors of modern Welsh, Cornish, and Breton, were carried to the British Isles somewhat later, probably in the second and first centuries BCE.
The Celtic presence in Iberia, traditionally called Celtiberia, dates to the late fourth and early third centuries BCE. The Celtiberians were a mixed Celtic and Iberian population who inhabited the central and western highlands of the Iberian Peninsula and who developed a distinctive culture that combined Celtic, Iberian, and Mediterranean elements. The Celtiberian tribes, including the Arevaci, Belli, Titti, and Lusones, played a major role in the history of pre-Roman Iberia, and their resistance to Roman expansion was among the fiercest outside of Italy. The Numantine War of 143 to 133 BCE, in which the Roman consul Scipio Aemilianus finally captured the Celtiberian city of Numantia after a long siege, was one of the defining events of the Roman conquest of Spain.
Expansion into the South: Italy and the Mediterranean
The Celtic expansion into the Italian peninsula began in the late fifth and early fourth centuries BCE, when Celtic war bands began to cross the Alps into the Po Valley. The Po Valley, with its rich agricultural land and its Etruscan and Venetic cities, was an attractive target, and by the mid-fourth century BCE, Celtic tribes including the Insubres, Cenomani, Boii, Lingones, and Senones had established themselves throughout the region. The Romans called these Celtic settlers the Galli Cisalpini, the Gauls of this side of the Alps, and they were to be a constant factor in Roman politics for the next two centuries.
The most dramatic moment of this southern expansion came in 390 or 387 BCE, when a Celtic war band under the Senones chieftain Brennus stormed the city of Rome itself. According to the Roman tradition, the Romans were defeated at the Battle of the Allia, a few miles north of the city, and the Gauls entered Rome and occupied most of it for several months before being bought off with a substantial ransom. The story of the geese of the Capitol, whose cackling woke the garrison and saved the citadel, has been a feature of Roman patriotic legend ever since. The historical reality behind the legend is debated, but there is no doubt that the sack of Rome was a real event, and its psychological impact on the Roman imagination was enormous.
In the third century BCE, Celtic war bands pushed even further south, raiding into Etruria, Umbria, and even Apulia. A great invasion of 284 BCE was defeated by the Romans at the Battle of Lake Vadimo, and a series of subsequent campaigns gradually reduced the Celtic presence in central Italy. By the early second century BCE, the Celtic tribes of the Po Valley had been defeated and incorporated into the Roman state, and the region became the Roman province of Gallia Cisalpina.
The Eastern Wanderung: The Balkans and Asia Minor
The most dramatic direction of Celtic expansion was to the east and southeast, into the Balkans and ultimately into Asia Minor. Beginning in the late fourth century BCE, large war bands of Celtic warriors began to move through the Danube basin and into the lands of the Thracians, the Illyrians, and the Macedonians. The motives behind this movement are debated, but they probably include a combination of population pressure, the search for loot, and the political vacuum created by the breakup of the Macedonian empire after the death of Alexander the Great.
The Celtic invasion of the Balkans reached its high point in 279 BCE, when a great host of Celtic warriors pushed south into Greece. According to the Greek sources, the Celts divided into three groups: one turned west into Illyria, one moved into Thrace, and the third, led by a chieftain named Cerethrius, marched south into Greece itself. The Greek city-states, weakened by decades of warfare and the recent upheavals of the Macedonian period, were unable to stop the invasion. The Celts attacked Macedonia, defeated the Macedonian king Ptolemy Keraunos in battle (he was one of the few Macedonian kings ever to die in combat against external enemies), and moved south into central Greece.
The climax of the Greek campaign came in 279 BCE, when a force of Celtic warriors attacked the sanctuary of Delphi. The Delphic accounts, written long after the event, claim that the god Apollo himself defended his sanctuary with an earthquake and a snowstorm, and that the Celts were driven back in confusion. Modern scholars are skeptical of this account, and it is possible that the attack on Delphi never actually took place, or that it was a smaller raid than the tradition suggests. What is clear is that the Celtic presence in Greece was short-lived, and that the main body of the invaders soon moved on. The route they took, and the farthest eastern point they reached, is traced in the account of the eastern Celtic movement.
The Galatian Kingdom
The third group of the Celtic invasion, under chieftains named Leonnorius and Lutarius, crossed the Hellespont into Asia Minor, where they were employed as mercenaries by various Hellenistic kings. In 275 BCE, the Celtic mercenaries of the Bithynian king Nicomedes I played a decisive role in his victory over his brother Zipoetes, and as a reward, Nicomedes granted them a territory in central Anatolia. This territory, in the region of modern Ankara, became the kingdom of Galatia, and the Celtic-speaking settlers became known as the Galatians. The Galatian story — the foundation of the kingdom, its three-tribe confederation, its wars, its Roman absorption in 25 BCE, its long survival into the early Christian period, and the remarkable persistence of its Celtic language into the fourth and fifth centuries CE — is told in the Celtic settlement of Galatia and in the broader story of how far east the Celts traveled.
The High Water Mark: The Celtic World at Its Height
By the late fourth and early third centuries BCE, the Celtic world had reached its greatest extent. From the Atlantic coast of Ireland to the plains of central Anatolia, from the fjords of Denmark to the Mediterranean coast of Spain, Celtic-speaking peoples and Celtic-influenced cultures dominated much of the European continent. The great tribal confederations of the period, including the Boii in central Europe, the Volcae Tectosages in the middle Danube and Galatia, the Senones in northern Italy and the Yonne valley, the Arverni in central Gaul, and the Helvetii in the Swiss plateau, were among the most powerful political entities in the ancient world, and their leaders could raise armies of tens of thousands of warriors.
The material culture of this vast Celtic world showed a remarkable degree of uniformity, expressed in the La Tène art style, in the use of iron swords and war chariots, in the roundhouse and the oppida, in the consumption of Mediterranean wine from elaborate bronze and silver vessels, and in the worship of a broadly shared pantheon of gods. A Celtic warrior in fourth-century BCE Bohemia would have recognized the swords, the shields, the brooches, and the feasting equipment of a contemporary in third-century BCE Galatia, and the religious specialists of one region would have been able to communicate with those of another across the breadth of the Celtic world.
This high water mark, however, was also the beginning of the end. The Celtic world was about to come into contact with two powers that would eventually transform or destroy it: the expanding Roman Republic in the south and the Germanic peoples in the north. The encounter with Rome that began with the sack of the Eternal City in 390 BCE would end, four centuries later, with the incorporation of almost the entire continental Celtic world into the Roman state. The Celtic-speaking peoples of the British Isles, beyond the reach of Roman arms, would continue to develop their own distinctive cultures, as the story of Celtic presence in the British Isles records.
Related Topics
- The origins and emergence of the Celts traces the roots of Celtic civilization in the late Bronze Age and early Iron Age heartland.
- The Celtic encounter with Rome examines the centuries of conflict and accommodation that followed the Celtic expansion into Italy.
- The Celtic presence in the British Isles follows the Celtic expansion to the western fringes of Europe.
- The La Tène and Hallstatt art styles provides the material culture framework for understanding the Celtic expansion.
- The Celtic tribal organization shaped the political structures of the great tribal confederations of the La Tène period.