The Roman Empire was involved in networks of trade, diplomacy, and influence that, at their greatest extent, spanned Europe, Africa, and Asia. In the north, a Roman glass cup was buried in a fourth-century grave mound in Føre, Norway, above the Arctic Circle. In the east, a Roman glass bowl was buried in a fifth-century tomb in the Nara Prefecture in Japan. In the south, four Roman beads made of glass, silver, and gold were deposited in a third-century context at a trading site at Mkukutu in Tanzania. While these finds trace the outer edges of the reach of Roman trade goods, these regions were too far from the empire to play much role in frontier society. It is doubtful whether the nobles and merchants of Norway, Japan, and Tanzania who received these objects had any conception of the Roman Empire or knew where the luxury goods in their possession had been made.
Some knowledge of Rome reached China, where the Roman Empire was called “Great Qin.” Chinese sources reflect some eclectic but not inaccurate knowledge of Roman geography, government, and law. Romans had a similarly vague knowledge of the Chinese, whom they called “Seres,” being aware that their land was the source of silk and lay to the east beyond Parthia and India, but contacts were neither direct nor regular enough to leave much trace on the frontiers. The peoples, networks, and power centers that had a stronger impact on the frontier were found closer to the territory that the Romans had claimed as their own.
In North Africa, Roman administration covered the coastal agricultural regions, but in the broad zone of marginal lands between the coast and the Sahara desert there were numerous peoples, known to the Romans by such names as Mauri, Gaetuli, and Garamantes, who lived partly in and partly beyond the frontier region. Some of these peoples were dry-zone farmers who managed large-scale irrigation works. Others lived as nomadic pastoralists. There has been a long debate in the scholarship whether the settled and nomadic peoples of Rome’s desert frontiers, in Africa and elsewhere, lived in a state of cooperation or competition; the answer may well be both, depending on local circumstances and the fortunes of their farms and herds.
South of Egypt, on the middle reaches of the Nile, was the kingdom of Kush. In the aftermath of Octavian’s victory over Antony and Cleopatra and the incorporation of Egypt into the empire, Roman and Kushite forces clashed over control of the borderlands. After brief hostilities, Queen Amanirenas of Kush sent ambassadors to make a treaty with Augustus, and the peace held for most of the next few centuries. Occasional diplomatic missions helped keep the peace. One of these, likely from the third century, appears to be documented by a Latin inscription at Musawwarat es-Sufra in which one Acutus from Rome formally presents his good wishes to an unnamed queen. Evidence for the study of Greek in Kush may represent local officials keeping up the necessary language skills to send their own ambassadors in return. Kush also participated in the trade routes that connected the Mediterranean with the Indian Ocean and central Africa. Concern for the security of trade may have encouraged both states to keep relations stable.
The Arabian frontier, like North Africa, presented a mix of settled kingdoms and nomadic peoples. The trade routes that passed through the region brought in substantial wealth but also further complicated the relationships between these societies. The Nabataean kingdom was a Roman client state for the better part of two centuries. Its capital at Petra was adorned with rock-cut temples in ornate Hellenistic style, and its kings were important regional leaders. Trajan annexed the territory in 107 as the province of Arabia Petraea, or “Rocky Arabia.” Other kingdoms and tribal alliances competed for power and control of trade routes, sometimes allying with Rome and sometimes raiding the frontier.
The largest and most powerful of Rome’s neighbors was the Parthian Empire. The Parthian state, though a match for Rome in its ability to muster forces for campaigning, was decentralized, prone to divisive court intrigue, and contained numerous semi-autonomous subkingdoms. The administration of this unruly empire was as unwieldy a task as the administration of the Roman Empire with its restless provincials and ambitious generals. It is no wonder that, in the first century CE, the two empires mostly contrived to leave one another alone. Nevertheless, Parthia loomed large in the Roman imagination. It remained the big prize, the enemy against whom flattering writers and propagandistic artists could always imagine emperors leading the good fight. Rome was equally significant to Parthian policy. The Parthian kings positioned themselves as heirs to the Achaemenid dynasty and champions of the Iranian peoples against western aggression.
The period of relative stability was broken by Trajan, who invaded Mesopotamia and Armenia in 113. Although Trajan’s conquests were quickly reversed by his successor Hadrian, Roman-Parthian relations remained unsettled for the following century. Several emperors initiated or contemplated military action against Parthia, and several Parthian kings pursued more aggressive policies on their western frontier. No substantial changes to the border were lasting, however, and diplomatic relations continued in between bursts of conflict. The historian Herodian even reports that the emperor Caracalla, in the early third century, proposed marrying a Parthian princess, and that Caracalla’s successor, Macrinus, celebrated a peace treaty and hailed the Parthian king Artabanus V as a loyal friend.
On the Black Sea steppes, a variety of nomadic and seminomadic peoples continued to live in traditional ways while some peoples of the region also developed settled kingdoms. Romans tended to describe the region in vague terms that drew as much on the literary tradition going back to Herodotus’ Scythians as they did on contemporary knowledge, but we should not assume that life on the steppe was static. Literary sources name various peoples in this region, including Sarmatians and Alans. In some cases, these names seem to correspond to identifiable ethnic and political groups, but they can also be unreliable, as the complexities of steppe identities were sometimes lost on writers from sedentary cultures.
In the late second century, there is evidence of cultural changes around the northern shores of the Black Sea and the lower Danube that may reflect the arrival of migrating warrior bands from somewhere to the north and west. These new peoples are reflected in a distinct archaeological pattern of settlement types, pottery styles, and burial practices. These features are the earliest evidence for a cultural pattern that would become more pronounced in the third and fourth centuries CE, which modern archaeologists have termed the Chernyakhov culture. It is generally believed that the Chernyakhov culture is related to the people known as “Goths” in the literary sources, but how consistent the Chernyakhov-Goth connection is and how early we can speak of a Gothic presence in the region are matters of debate.
The Romans referred to the peoples who lived along the middle to upper Danube and Rhine as “Germans” (barring a few exceptions, such as the Dacians and Iazyges), but it is unlikely that the tribes and kingdoms of this region felt any kind of shared identity. Many individual tribal names are also known, but, as elsewhere, we cannot be confident that the Roman authors who recorded those names were applying them accurately. Many cultures existed in this region with different kinds of social and political organization. Some, such as the Dacians and Marcomanni, appear to have reached an early stage of state development, with power centralized in well-established royal families. Other peoples, such as the Frisians, lived in small, egalitarian communities with little in the way of formal power structures.
Farther to the north, away from the frontier zone but in close contact with the Roman world, another major power was rising. At Himlingøje in Denmark, a group of lavish burials filled with Roman luxuries marks the center of a commercial and political network that established itself in the late second century and spanned the Baltic Sea and southern Scandinavia. The warrior nobles of Himlingøje fought as auxiliaries in the Roman army and maintained strong trade and diplomatic connections to Rome after they returned home. Through these connections they acquired Roman goods, which they then used as prestigious gifts to expand their network of influence in the North. The numerous ritual deposits they made in Danish bogs of the weapons and armor of their defeated enemies show that they expanded their power in more aggressive ways as well. While many of the peoples who lived closer to the Roman frontier had unsettled histories with Rome, the rulers of Himlingøje appear to have remained on good terms with the Romans throughout their history.
Rome also had staunch allies in Scotland with the Votadini whose power center, a fortified hilltop site at Traprain Law, has yielded an extraordinary wealth of Roman imports ranging from gold brooches to iron door hinges. The precise boundaries of Votadinian power are uncertain, but other peoples certainly lived beyond the British frontier, both in Scotland and Ireland. Some of these peoples had large, settled societies, but others were small and mobile.
The peoples who lived in and beyond the Roman frontier zone varied widely in their ways of life, social organization, and political structures. While some maintained long-term diplomatic ties with Rome, others had volatile relations with the empire. This wide variety of frontier peoples challenged Rome’s limited capacity for maintaining foreign relations and managing the frontiers.
Emperors and Frontiers
The frontier was always an area of special concern to the emperors, even those with little direct experience of it. Imperial power depended on the support of two groups: the army, which was mostly stationed on the frontiers, and the people of Rome, who approved of victories over barbarians. Although imperial activity on the frontier could be haphazard and inconsistent, few emperors could afford to ignore the frontier entirely.
After the defeat of Varus, Augustus soured on expansion. He initiated no more conquests, and his final advice to his successor Tiberius was to keep the empire within its boundaries. The meaning of this counsel has long been debated. It is unlikely he meant that the empire should never expand again. The conquering ideal remained fixed in Roman ideology, and Augustus was not shy of bragging about the conquests accomplished under his authority. More likely it was personal advice to his successor not to embark on a new series of foreign campaigns for political purposes.
On the whole, most of Augustus’ successors followed his advice. On the grand scale, the frontier was mostly stable. There were only a few large additions to the empire in the following centuries: the southern half of Great Britain, parts of North Africa, Dacia, parts of Arabia, Armenia, and Mesopotamia. The conquests of Mesopotamia and Armenia were brief accomplishments of Trajan’s and Septimius Severus’ wars against Parthia and did not long endure. Some of the expansions in Africa and Arabia came from incorporating client kingdoms rather than conquering new lands. On the small scale, however, the frontier was turbulent. Almost every emperor from Augustus to Severus Alexander fought frontier campaigns or faced unrest in frontier provinces. Most of these campaigns added little, if any, new territory to the empire, but few emperors actually treated the frontier as a limit not to be crossed.
Emperors who felt insecure in their position used foreign wars to prove their worth in the traditional expansionist mode. Claudius, who came to power unexpectedly, initiated the conquest of Britain, which the unloved Nero continued. Domitian, another surprise emperor, began his reign with a campaign in Germany that even his fellow Romans criticized as unwarranted. Trajan, though he grew to be one of the most beloved emperors, came to power through obscure political machinations, which may help explain his ambitious program of conquests in Dacia and Mesopotamia. Septimius Severus, the victor of a civil war, spent much of his reign fighting in Mesopotamia, North Africa, and Scotland. These campaigns not only showered military glory on the emperors but also enriched the empire with plunder and slaves while keeping potentially restless soldiers occupied.
Restless soldiers were no trifle. Revolt by troops who felt ignored by the emperors was a recurrent threat to imperial stability. Sometimes this discontent could be softened by letting the soldiers pillage across the frontier. On other occasions, successful frontier generals could harness their soldiers’ dissatisfaction in a bid for the throne. Vespasian and Septimius Severus both came to power in this way, and many more attempted the feat unsuccessfully or managed it only to be quickly ousted by a rival general.
While the Romans pushed the frontier, the frontier pushed back. There were few major incursions on Roman territory in the first centuries of the empire, but some threats demanded the emperor’s attention. Relations with the Parthian Empire remained unresolved as both empires pressed for greater influence along their mutual border, but neither could secure a lasting victory over the other. Trajan, Severus, and Caracalla all led major campaigns against Parthia, but their gains did not last. The Parthians backed Pescennius Niger, a general in Syria who competed with Severus for power, but Pescennius’ bid for the throne failed.
Away from the Parthian front, the most serious threat to the Roman frontier in this period developed along the Danube in the late second century. Termed the Marcomannic Wars by modern scholarship, this diffuse and protracted series of conflicts involved many of the peoples of the region, chiefly the Marcomanni, Quadi, and Iazyges, and kept the emperor Marcus Aurelius occupied from the early 160s to 180. Smaller-scale troubles rarely claimed the attention of the emperors, but raiding, local resistance, and discontent among the soldiers were constant nuisances in the frontier zone that could flare up into more serious trouble if not kept in check.
Emperors undertook a variety of different policies toward the frontier. In the early empire, rulers such as Augustus and Nero were content to govern from a distance and entrust even major campaigns to subordinates, but the rise of frontier generals as claimants to the throne demonstrated that it was dangerous for an emperor to leave the frontier in anyone else’s hands. There were those, such as Trajan and Severus, who threw themselves into aggressive frontier campaigning. Others, notably Hadrian and Marcus Aurelius, were led, either by temperament or circumstance, to focus on consolidating and defending the territory claimed by their predecessors. Only a few emperors such as Antoninus and Elagabalus largely ignored frontier problems, being either fortunate enough to rule in a period of relative calm or else too busy with their own concerns.
Because of the practicalities of governing a continent-spanning state in an age when messages could take weeks and armies months, if not years, to reach the frontier, an emperor’s ability to effectively manage the frontier was limited. At the same time, as proven by generals such as Vespasian and Severus, delegation of too much power was risky. Wars against barbarians or restless provincials were potent propaganda tools, and emperors were wary of letting anyone else get their hands on them. It was a conventional charge against bad emperors that they did not trust their subordinates, but even the most popular emperors understood the importance of preserving personal control over frontier policy. After the Julio-Claudian age, most emperors learned to keep frontier generals on a short leash.