12 Transformation of the Mediterranean World

Imperial instability and division

From the third century CE, the Roman Empire faced repeated civil wars, rapid changes of emperor, frontier invasions, and growing costs of administration and defense. These pressures reinforced one another: rival claimants drew troops into internal conflict, while emperors needed more soldiers and revenue to secure the frontiers. The empire did not collapse all at once. Emperors responded with reforms, including expanded administration and military reorganization associated with Diocletian and Constantine.

Constantine founded Constantinople at a strategic crossroads between Europe and Asia. Its position connected Black Sea routes with Mediterranean shipping, helping it become a major imperial center. In 395, after Theodosius I died, the empire was governed by separate eastern and western courts. This division did not immediately end the idea of a Roman Empire. The eastern government had wealthier, more urbanized provinces and a stronger base for collecting revenue and maintaining armies.

The western government fragments

The western government struggled to control territory and pay for defense. Groups including Goths and Vandals invaded or settled within imperial territory amid internal power struggles; they were not a single invading force that brought Rome down. Losing provinces reduced tax income and access to resources. Rome was sacked in 410, and in 476 the western emperor Romulus Augustulus was deposed.

The year 476 is a useful marker for political change, not a sudden end to Roman life. Successor kingdoms ruled former imperial lands, often keeping Roman laws, officials, and customs. The eastern Roman Empire continued, and its people understood their state as Roman.

Christianity reshapes public life

Christianity grew within the diverse religious world of the Roman Empire. Constantine and Licinius agreed in 313 to legalize Christian worship; this did not immediately make Christianity the sole religion. Imperial support increased over the fourth century, and Theodosius I made Nicene Christianity the empire’s official religious standard in 380. Traditional cults and different Christian communities nevertheless persisted, and religious change unfolded unevenly across regions and generations.

Bishops became influential leaders in cities, while churches and pilgrimage centers reshaped urban landscapes. Christian art developed alongside classical forms. The eastern Roman Empire remained Christian and Roman in its political identity. Western kingdoms also adopted Christianity, often through the conversion of rulers and their peoples. Christianity helped create connections across political boundaries, but it was not the sole cause of the western empire’s fragmentation; military, fiscal, and political pressures were central as well.

Trade and economic pressures

Mediterranean regions depended on one another through shipping, taxation, and trade. North African grain and other goods supplied markets, and cities and ports linked producers with consumers across long distances. When the Vandals captured Carthage in 439, the western government lost an important province and source of revenue. Trade did not simply disappear: goods continued to move, though routes, political authorities, and beneficiaries changed. Economic change was regional and gradual, not a uniform collapse.

Wars and changing imperial power

The eastern empire also faced severe military strain. In the sixth century, Emperor Justinian reconquered parts of North Africa and Italy, briefly restoring Roman rule across much of the Mediterranean. These campaigns brought territory but required extensive military resources. In the early seventh century, prolonged wars between Byzantium and the Sasanian Empire further weakened both powers.

Arab Muslim armies then took major Byzantine territories, including Syria, Egypt, and North Africa. By the early eighth century, Muslim rule also extended across much of Iberia.

A connected but diverse Mediterranean

The Mediterranean did not become a single political or religious world after the western Roman government ended. It became a region of competing and interacting states: western successor kingdoms, the eastern Roman Empire—often called Byzantium by modern historians—and expanding Muslim caliphates. Constantinople remained a major Christian imperial capital, while Damascus became the Umayyad caliphate’s capital. Greek, Latin, and Arabic gained importance in different regions, while local languages and traditions continued.

New borders and rulers changed taxation, military control, and political allegiance, but older cities, trade routes, artistic practices, and administrative traditions often endured. Early Islamic art and government drew on Byzantine and Sasanian precedents while developing distinctive forms. The Mediterranean was transformed, not cut off from its past, into a connected but politically and religiously diverse world.

• western Roman Empire