Western Southeast Europe (820 – 963 CE): Byzantine Greece, Slavic Principalities, and the Adriatic City-Ports

Geographic and Environmental Context

Western Southeast Europe includes Greece (outside Thrace), Albania, Montenegro, North Macedonia, Kosovo, most of Bosnia, southwestern Serbia, most of Croatia, and Slovenia.

• Coastal lowlands and islands along the Adriatic (Dalmatia, the Ionian isles) met the Dinaric and Pindus mountains’ karst and upland pastures.

• Interior corridors—Morava–Vardar, Drina–Sava, and the Via Egnatia from Dyrrachium (Durres) to Thessaloniki—linked the Aegean and Adriatic to the central Balkans.

• River valleys and Mediterranean basins of Attica, Boeotia, Peloponnese, and Epiros anchored Byzantine agrarian themes.

Climate and Environmental Shifts

• A Mediterranean–continental mix: wet winters and dry summers on the coasts; cooler, more variable regimes inland.

• Toward the 10th century, the onset of the Medieval Warm Period slightly lengthened growing seasons, aiding vine and olive culture in Greece and mixed cereal–pastoral economies inland.

Societies and Political Developments

• Byzantine Greece:

  • The empire reasserted control over earlier Slavic settlements (Sklaviniai) in Hellas and the Peloponnese, strengthening the Themes of Hellas and Peloponnēsos.

  • Under Basil I (867–886) and Leo VI (886–912), fort networks and fiscal-military administration recovered towns; Constantine VII (r. 913–959) codified provincial governance.

  • Monastic revival culminated at the end of the age with St. Athanasios founding the Great Lavra (963) on Mount Athos, inaugurating the Athonite commonwealth.

• Dalmatian coast & Adriatic cities (Split, Zadar, Trogir, Ragusa/Dubrovnik):

  • Urban municipalities under Byzantine suzerainty (with Latin civic traditions) acted as maritime hubs between Venice, southern Italy, and the Aegean; local comites and councils balanced imperial interests and city autonomy.

• Croatia:

  • The Duchy of Croatia consolidated in the 9th century; Christianity advanced under Frankish and papal influence.

  • Tomislav (traditionally crowned c. 925) forged a Kingdom of Croatia, mediating between Byzantium (Dalmatian cities) and the interior.

  • Glagolitic liturgy (from the missions of Cyril and Methodius) took root alongside the Latin rite.

• Serbian lands (Raška, Zahumlje, Travunija, Duklja/Dioclea):

  • The Vlastimirović dynasty (Serbia/Raška) and coastal principalities in Zahumlje (Herzegovina), Travunija, and Duklja (Montenegro) navigated between Byzantine, Bulgar, and later Croatian pressures.

  • Baptism and church-building progressed unevenly; župans governed district polities (župe) from hillforts (gradine).

• Bosnia & inland Slovenia:

  • Clustered hillfort communities under local župans and counts emerged along the Drina–Bosna–Vrbas and Sava corridors, tied to Croatian and Frankish spheres.

• North Macedonia & Kosovo:

  • Slavic communities in Macedonia and the Vardar basin faced alternating Byzantine and Bulgar influence; Thessaloniki remained the imperial anchor in the region.

  • The cultural afterglow of the Cyril–Methodius mission (863) radiated west via disciples and scriptoria.

Economy and Trade

• Agriculture:

  • Greece—olives, vines, wheat, and garden crops under village commons and monastic estates.

  • Uplands—transhumant flocks; lowlands—cereal rotations; coastal lagoons—salt and fish.

• Trade:

  • Via Egnatia moved Balkan grain, timber, and wax from Dyrrachium to Thessaloniki and Constantinople.

  • Adriatic shipping linked Dalmatian cities to Venice and Apulia; Byzantine nomismata and Italian denarii circulated with cloth, wine, ceramics, and metalware.

  • Interior market nodes (e.g., Skopje, Niš) exchanged hides, honey, wax, and slaves for Mediterranean goods.

Subsistence and Technology

• Terrace agriculture in Greek highlands; irrigation channels and cisterns in lowland plains.

• Pastoral transhumance across Dinaric and Pindus slopes; wool and hides fed urban workshops.

• Ship types: Byzantine dromōn and coastal transports; Dalmatian galleys and coasters; standardized amphorae and barrels for wine/oil.

• Fortifications: stone kastra along roads and passes; timber–earth hillforts (gradine) in inland Slavic zones.

• Scripts: Latin in the Adriatic cities; Greek in Byzantine administration; Glagolitic (later Cyrillic) permeated Slavic ecclesiastical use.

Movement and Interaction Corridors

• Via Egnatia: Dyrrachium–Thessaloniki–Constantinople, the main imperial artery.

• Morava–Vardar corridor: interior route from the middle Danube to the Aegean.

• Adriatic sea-lanes: Venice ⇄ Dalmatia ⇄ Greece; island chains served as stepping-stones.

• Mountain passes (e.g., Katara, Metsovo, Ivan): controlled troop movement and caravan traffic.

Belief and Symbolism

• Orthodox Christianity dominated Byzantine Greece; icons, relic cults, and monastic patronage shaped sacred geography (Athos, Meteora precursors).

• Latin Christianity prevailed in Dalmatian municipalities and among Croatian elites; rivalry and cooperation with Byzantium coexisted.

• Slavic Christianization advanced via Cyril–Methodius’ Slavic liturgy and local bishoprics; pagan survivals persisted in upland communities.

• Crosses on hillforts, basilicas in towns, and rural shrines marked the Christianization landscape.

Adaptation and Resilience

• Theme (provincial) systems mobilized local troops and taxes, enabling Byzantine Greece to weather raids and recover lands.

• Maritime redundancy—Adriatic and Aegean lanes—kept trade moving when inland conflict flared.

• Dual rites—Latin and Greek—reduced friction at the Adriatic–Aegean interface by embedding diplomacy in liturgy.

• Hillfort + kastron pairing allowed interior polities to buffer against Bulgar pushes and raiding.

Long-Term Significance

By 963 CE, Western Southeast Europe was a braided frontier:

• Byzantine Greece reestablished provincial depth and spiritual authority (Athos at the close of the age).

• Croatia crystallized into a kingdom, mediating Adriatic and inland interests.

• Serbian principalities and Macedonian Slavs balanced between Bulgaria and Byzantium.

• Dalmatian cities prospered as Adriatic brokers under imperial suzerainty.
  These dynamics set the stage for the Bulgar–Byzantine wars of the next age, the Adriatic rise of Venice, and the maturation of Slavic Christian polities across the western Balkans.

Most historians believe that the Croats are a purely Slavic people who probably migrated to the Balkans from present-day Ukraine.

A newer theory, however, holds that the original Croats were nomadic Sarmatians who roamed Central Asia, migrated onto the steppes around 200 BCE, and rode into Europe near the end of the fourth century CE, possibly together with the Huns.

The Sarmatian Croats, the theory holds, conquered the Slavs of northern Bohemia and southern Poland and formed a small state called White Croatia near present-day Kraków.

The Croats then supposedly mingled with their more numerous Slavic subjects and adopted the Slavic language, while the subjects assumed the tribal name "Croat."

A tenth-century Byzantine source reports that in the seventh century Emperor Heraclius enlisted the Croats to expel the Avars from Byzantine lands.

The Croats had overrun the Avars and Slavs in Dalmatia around 630, then drove the Avars from today's Slovenia and other areas.

In the eighth century, the Croats lived under loose imperial rule, and Christianity and Latin culture recovered in the coastal cities.

The Franks subjugated most of the Croats in the eighth century and sent missionaries to baptize them in the Latin rite, but the Byzantine Empire continued to rule Dalmatia.

Croatia emerges as an independent nation in 924.

Tomislav (910-ca. 928), a tribal leader, establishes himself as the first king of Croatia, ruling a domain that stretches eastward to the Danube.

Tomislav, the local ruler (zupan) of Nin, unites the Croat tribes of Dalmatia and Pannonia to form a kingdom in 924.

Pope John X recognizes Tomislav as the first king of Croatia in 925 .

Croatian bishop Grgur (Gregory) of Nin successfully presses for the independence of the Latin-rite diocese of Nin from …

…the older Greek-rite archdiocese of Split, as well as for the right of the Croat church to employ the Slavonic liturgy and the Glagolitic, or Cyrillic, alphabet.

Simeon's troops under Alogobotur invade Croatia in 926, at this time an ally of Constantinople.

The reason might have been that Tomislav had received and protected the Serbs who were expelled by Simeon from Rascia.

In all probability, however, the main reason is that Simeon, if crowned by the Papal Legate, fears an attack from the Emperor Romanos Lekapenos, supported by Tomislav.

Romanos had won the friendship of Tomislav some years previously, handing over Dalmatia to Tomislav and recognizing him as King of Croatia (Pope John X had recognized Tomislav as King of Croatia in 925).

Tomislav had sent his troops to Italy during the summer of 926 to expel Saracens from the city of Sipontus, which belongs to the imperial province of Langobardia.

This event could have been sufficient proof to Simeon that the Croats had taken the side of Constantinople and that they would support the Greek emperor actively in the future.

Therefore, when Simeon sends a great army against the Croats, the Bulgarians are met by Tomislav's army in the mountainous region of Eastern Bosnia.

The Croatian forces under the leadership of their king completely devastate the Bulgarian army.

Key to Tomislav's triumph is likely the choice of terrain on which the battle takes place: Croatian soldiers are probably more skilled in fighting in the mountainous terrain of the Bosnian highlands.

The Croatian victory is so decisive and the battle so big that contemporary sources greatly overestimate Croatia's army at one hundred and sixty thousand men, with a slightly bigger force on the Bulgarian side.

This is the only battle Tsar Simeon ever loses.

Since both rulers maintain good relations with John X, the pope is able to negotiate an end to the war soon afterward without any further border changes.

Tomislav, fearing Bulgarian retribution, accepts to abandon his union with Constantinople and make peace on the basis of the status quo, negotiated by the papal legate Madalbert.

Bulgaria has reached its cultural apogee during Simeon's reign, becoming the literary and spiritual center of Slavic Europe.

In this respect, Simeon has continued his father Boris' policy of establishing and spreading Slavic culture and attracting noted scholars and writers within Bulgaria's borders.

It is in the Preslav Literary School and Ohrid Literary School, founded under Boris, that the main literary work in Bulgaria has been concentrated during the reign of Simeon.

By the close of Simeon’s five-year campaign against the Empire, the Bulgarian khan has conquered most of Serbia, advanced to the walls of Constantinople four times, compelled Constantinople to pay him tribute, and driven the Empire’s Magyar allies into the Plain of Hungary.

In the last months of his life, Simeon prepares for another siege of Constantinople despite Romanos' desperate pleas for peace.

He dies of heart failure in his palace in Preslav on May 27, 927.

Byzantine chroniclers tie his death to a legend, according to which Romanos decapitated a statue which was Simeon's inanimate double, and he died at that very hour.

Twice married, Simeon leaves four sons, of whom the second, Peter, succeeds him, with George Sursuvul, the new emperor's maternal uncle, initially acting as a regent.

The long Bulgarian-Byzantine War ends with Simeon's death.

As part of the peace treaty signed in October 927 and reinforced by Peter's marriage to Maria (Eirene), Romanos' granddaughter, and with it an annual tribute.

The existing borders are confirmed, as are the Bulgarian ruler's imperial dignity and the head of the Bulgarian Church's patriarchal status.

This agreement will usher in a period of forty years of peaceful relations between the two powers, a time of stability and prosperity for Bulgaria.

Much of Bosnia is taken over after the death of Tomislav in 928 by a Serb princedom that acknowledges the sovereignty of Constantinople.

The first recorded mention of Bosnia is written during this period by the the Greek emperor Constantine VII Porphyrogenitus, whose writings are one of the best sources of information on the Greek empire and neighboring areas.

Describing “Bosona” as a district in “baptized Serbia,” the district he refers to is an area much smaller than modern Bosnia and centered on the Bosna River.

Soon after Constantine writes those words, most of the modern territory of Bosnia reverts to Croatian rule.

Western Southeast Europe (964 – 1107 CE): Basil II’s Balkans, Croatian–Hungarian Ties, and Communal Dalmatia

Geographic and Environmental Context

Western Southeast Europe includes Greece (outside Thrace), Albania, Montenegro, North Macedonia, Kosovo, most of Bosnia, southwestern Serbia, most of Croatia, and Slovenia.

• Coastal lowlands and islands along the Adriatic (Dalmatia, the Ionian isles) met the Dinaric and Pindus mountains’ karst and upland pastures.

• Interior corridors—Morava–Vardar, Drina–Sava, and the Via Egnatia from Dyrrachium (Durres) to Thessaloniki—linked the Aegean and Adriatic to the central Balkans.

• River valleys and Mediterranean basins of Attica, Boeotia, Peloponnese, and Epiros anchored Byzantine agrarian themes.

Climate and Environmental Shifts

• Warm conditions persisted; viticulture and herding thrived along coast-and-upland belts; river ice-free seasons lengthened shipping cycles.

Societies and Political Developments

• Byzantium under Basil II (r. 976–1025) dismantled the First Bulgarian Empire (1018), restoring imperial control across Macedonia, Kosovo, and Greece outside Thrace; the catepanates and themes stabilized taxation and law.

• Croatia remained a kingdom but, after dynastic ebb, entered a personal union with Hungary (1102), while coastal communes negotiated with Venice.

• Serbian principalities (Raška, Zeta) oscillated between Byzantine and local autonomy; Vukan’s line rose late in the period.

• Dalmatian communes—Zadar, Split, Trogir, Kotor, Ragusa—balanced Byzantine, Venetian, and Hungarian pressures, codifying statutes and expanding harbors.

• Epirus and Achaea (within this Greece definition) remained Byzantine; local aristocracies accrued weight in the Komnenian ascent on our period’s horizon.

Economy and Trade

• Silver and iron from inland Bosnia/Serbia moved to Dalmatia; salt pans (e.g., Pag) underwrote fiscal systems.

• Adriatic convoys—often Venetian—linked Dalmatia to Apulia, Ancona, and Constantinople; Via Egnatia fed Dyrrhachium and inland markets.

Subsistence and Technology

• Stone fortifications proliferated (coastal walls, inland strongholds); shipyards built cogs and galleys; notarial records standardized credit.

Movement and Interaction Corridors

• Adriatic lanes: Venice–Dalmatia–Apulia.

• Vardar–Morava axis integrated Skopje and Niš with Aegean and Danubian worlds.

• Sava–Drava tied Croatia/Slovenia to Central Europe.

Belief and Symbolism

• Orthodox monasteries (e.g., Ohrid as an ecclesiastical hub) flourished; Latin mendicants expanded in Dalmatia.

• Relic cults and processions legitimized communal and princely authority.

Adaptation and Resilience

• Triangular diplomacy—Byzantine, Hungarian, Venetian—kept corridors open.

• Communal statutes/consulates lowered risk for merchants.

Long-Term Significance

By 1107, Byzantine administration was restored inland; Croatia–Hungary alignment, Serbian consolidation, and Dalmatian communal strength set the stage for 12th-century transformations.

Samuel launches a major campaign against the Serbian principality of Duklja in 998 to prevent an alliance between Prince Petrislav and Constantinople.

When the Bulgarian troops reach Duklja, the Serbian prince and his people withdraw to the mountains.

Samuel leaves part of the army at the foot of the mountains and leads the remaining soldiers to besiege the coastal fortress of Ulcinj.

In an effort to prevent bloodshed, he asks Petrislav to surrender.

After the prince refuses, some Serb nobles offer their services to the Bulgarians and, when it becomes clear that further resistance is fruitless, the Serbs surrender.