The Dacian king Duras again orders his troops to attack Roman Moesia in 86.

After this attack, the Roman emperor Domitian personally arrives in Moesia and in August 86 and reorganizes it into two provinces, divided by the river Cebrus (Ciabrus): to the west Moesia Superior—Upper Moesia, (meaning up river) and …

…to the east Moesia Inferior—Lower Moesia (also called Ripa Thracia), (from the Danube river's mouth and then upstream).

Each is governed by an imperial consular legate and a procurator.

Domitian transfers three additional legions to the Danube and plans an attack into Dacia for the next campaign season.

It does not turn out well.

Tettius Iulianus commands another Roman army under Domitian against the Dacians, who in late 88 deals the Romans a severe defeat the Romans at the Second Battle of Tapae, the same site where Fuscus had perished in a previous engagement.

Decebalus, the newly crowned king of Dacia, in unifying the various Getian and Dacian tribes into one nation centering on modern Romania, has established a new Geto-Dacian state, constructed a system of fortresses, and outfitted an army, raiding southward across the Danube.

It is fortunate for Decebalus that the pretender Saturninus, commander in Upper Germany, has rebelled against Emperor Domitian and that certain of the German tribes in the West choose this moment to revolt against Rome.

The new danger causes Domitian to come to terms quickly with Decebalus in 89 and to provide the Getae with a subsidy and loan of engineers in exchange for recognition of Roman overlordship and Decebalus' protection of the lower Danube against Sarmatian attack.

The Romans are compelled to pay large sums in tribute to the Dacians for maintaining peace, as German revolts along the Rhine are requiring augmented military force in Moesia.

This humiliating situation lasts until Trajan becomes Emperor in 98.

Immediately, he begins preparations for wars that will result in the expansion of the Roman Empire to its maximum extent.

Eastern Southeast Europe (100–243 CE): Stability, Crisis, and Regional Transformation

Settlement and Migration Patterns

Continued Roman Urbanization and Development

Between 100 and 243 CE, Eastern Southeast Europe experienced sustained urban growth under Roman administration. Cities such as Byzantium and Philippopolis (modern-day Plovdiv) thrived as key regional hubs, featuring monumental architecture, forums, temples, water systems, coliseums, and public baths. Urban centers expanded with robust infrastructure, attracting diverse populations and fostering economic and cultural vitality.

Establishment of Roman Provinces

Significant Roman administrative reorganizations occurred, leading to the creation of new provinces, notably Roman Dacia (106 CE), Moesia Inferior, and Thracia. Emperor Trajan organized Dacia following his victory over the Getae, establishing the provincial capital at Ulpia Trajana on the site of Sarmizegetusa. The province attracted colonists from various parts of the Roman Empire, including Gaul, Spain, and Syria, contributing to regional stability and economic integration.

Increasing Migration and Border Pressures

This era witnessed increasing pressures from migrating groups along the empire's northern borders, notably Goths and other Germanic tribes, impacting regional stability. These movements foreshadowed later significant migrations and conflicts, influencing settlement patterns and military strategies.

Economic and Technological Developments

Economic Prosperity and Regional Trade

Economic activities flourished, supported by Roman trade networks, agricultural productivity, and mining industries, notably gold and silver mining in Dacia. The region benefited significantly from its strategic geographic position, facilitating trade connections between Europe, Asia Minor, and the broader Mediterranean.

Technological Continuity and Infrastructure Maintenance

Roman technological innovations supported economic stability, particularly in agricultural efficiency, mining, and infrastructure management. Aqueducts, roads, and ports were actively maintained and expanded, ensuring regional prosperity and connectivity. The introduction of viticulture in regions like Dalmatia and the development of iron metallurgy with iron plowshares and other agricultural implements enhanced productivity.

Cultural and Artistic Developments

Cultural Continuity and Artistic Expression

Artistic traditions reflected sustained cultural synthesis, blending Roman, Greek, and indigenous Thracian elements. Public monuments, statues, mosaics, frescoes, and ceremonial artifacts decorated urban spaces, demonstrating cultural pride and regional identity.

Literary and Intellectual Growth

Urban centers became hubs of intellectual and literary activities, reflecting Roman educational standards and Greek philosophical traditions. Schools, libraries, and theaters fostered cultural vitality, intellectual exchanges, and literary production, promoting widespread literacy and the gradual adoption of Latin in daily and administrative life.

Social and Religious Developments

Provincial Administration and Social Integration

Roman governance structures integrated local elites into imperial administration, strengthening societal coherence. Roman citizenship expanded, assimilating indigenous populations into Roman social and political frameworks. Notably, the Roman army recruited natives from conquered regions, and five Illyrian-born individuals rose through military ranks to become emperors.

Religious Diversity and Emergence of Christianity

Religious diversity characterized the region, with traditional Roman, Greek, and local religious practices coexisting. The mystic cult of Mithras, introduced by Roman legionnaires from Persia, gained popularity alongside existing local beliefs. Christianity also spread notably throughout Eastern Southeast Europe, establishing early communities and becoming increasingly influential in urban and provincial areas.

Long-Term Consequences and Historical Significance

The period from 100 to 243 CE was marked by urbanization, economic prosperity, and increasing regional pressures from migrations. The establishment of Roman Dacia and other provinces significantly impacted local societies, economy, and culture. The Roman influence decisively shaped the evolution of indigenous populations such as the Getae, resulting in a distinct Dacian ethnic group as Roman colonists intermingled with local and Greek coastal populations. These developments laid foundations for future transformations, particularly the rise of Christianity and increasing border challenges, profoundly influencing regional historical trajectories.

Latin culture permeates southeastern Europe over the next five hundred years.

The Romans divide their western Balkan territories into separate provinces.

New roads link fortresses, mines, and trading towns.

The Romans introduce viticulture in Dalmatia, institute slavery, and dig new mines.

Agriculture thrives in the Danube Basin, and towns throughout the country blossom into urban areas with forums, temples, water systems, coliseums, and public baths.

In addition to gods of the Greco-Roman pantheon, Roman legionnaires bring the mystic cult of Mithras from Persia.

The Roman army also recruits natives of the conquered regions, and five sons of Illyrian peasants will rise through the ranks to become emperor.

The Illyrian, Celtic, and Thracian languages will all eventually die out, but the centuries of Roman domination will fail to create cultural uniformity.

Emperor Trajan employs Apollodorus in Dacia to build a bridge across the Danube (pictured on Trajan's Column).

Its twenty stone masonry piers—one hundred and fifty feet (forty-five meters) high, sixty feet (eighteen meters) wide, and one hundred and seventy feet (fifty-two meters) apart—support the span’s wooden superstructure.

The Dacians, or Getae, had been left independent after Domitian’s Dacian Wars in the late 80s, their king, Decebalus, having received the status of "king client to Rome", receiving from Rome military instructors, craftsmen and even money.

Instead of using the money as Rome intended, Decebalus had elected to build new citadels in the mountains in important strategic points and to reinforce the existing ones.

Trajan, determined to stamp out the Getian menace, expand the glory of his reign, end a treaty perceived as humiliating, and take over the gold and silver mines of Transylvania, has decided to strengthen the dangerous Danube frontier by converting Dacia into a salient of Roman territory north of the river.

This would also dismember the Sarmatian tribes and remove the risk of large, hostile combinations to a safer distance.

Labeling Decebalus a menace to the security of Rome’s provinces to the south across the Danube, Trajan assumes personal command of a punitive expedition of the Dacian kingdom and, with a force of one hundred thousand men, launches his first campaign in 101.

The Romans lay down a road along the Danube and cross the river at Viminacium, slowly making their way into Dacia.