page_title: Greece
section_title: Medieval period (4th – 15th century)
hierarchical_section_title: Greece / History / Medieval period (4th – 15th century)
caption_attribution_description: English: Dome with mosaic of Hagia Sophia in Thessaloniki
context_page_description: Greece, officially the Hellenic Republic, known also as Hellas, is a country located in Southeast Europe. Its population is approximately 10.7 million as of 2018; Athens, the nation's capital, is its largest city, followed by Thessaloniki.
  Situated on the southern tip of the Balkans, Greece is located at the crossroads of Europe, Asia, and Africa. It shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to the northeast. The Aegean Sea lies to the east of the mainland, the Ionian Sea to the west, the Cretan Sea and the Mediterranean Sea to the south. Greece has the longest coastline on the Mediterranean Basin and the 11th longest coastline in the world at 13,676 km in length, featuring many islands, of which 227 are inhabited. Eighty percent of Greece is mountainous, with Mount Olympus being the highest peak at 2,918 metres. The country consists of nine traditional geographic regions: Macedonia, Central Greece, the Peloponnese, Thessaly, Epirus, the Aegean Islands, Thrace, Crete, and the Ionian Islands.
context_section_description: The Roman Empire in the east, following the fall of the Empire in the west in the 5th century, is conventionally known as the Byzantine Empire (but was simply called "Roman Empire" in its own time) and lasted until 1453. With its capital in Constantinople, its language and literary culture was Greek and its religion was predominantly Eastern Orthodox Christian.
  From the 4th century, the Empire's Balkan territories, including Greece, suffered from the dislocation of barbarian invasions. The raids and devastation of the Goths and Huns in the 4th and 5th centuries and the Slavic invasion of Greece in the 7th century resulted in a dramatic collapse in imperial authority in the Greek peninsula. Following the Slavic invasion, the imperial government retained formal control of only the islands and coastal areas, particularly the densely populated walled cities such as Athens, Corinth and Thessalonica, while some mountainous areas in the interior held out on their own and continued to recognise imperial authority. Outside of these areas, a limited amount of Slavic settlement is generally thought to have occurred, although on a much smaller scale than previously thought. However, the view that Greece in late antiquity underwent a crisis of decline, fragmentation and depopulation is now considered outdated, as Greek cities show a high degree of institutional continuity and prosperity between the 4th and 6th centuries AD (and possibly later as well). In the early 6th century, Greece had approximately 80 cities according to the Synecdemus chronicle, and the period from the 4th to the 7th century AD is considered one of high prosperity not just in Greece but in the entire Eastern Mediterranean.
  Until the 8th century almost all of modern Greece was under the jurisdiction of the Holy See of Rome according to the system of Pentarchy. Byzantine Emperor Leo III moved the border of the Patriarchate of Constantinople westward and northward in the 8th century.
  The Byzantine recovery of lost provinces began toward the end of the 8th century and most of the Greek peninsula came under imperial control again, in stages, during the 9th century. This process was facilitated by a large influx of Greeks from Sicily and Asia Minor to the Greek peninsula, while at the same time many Slavs were captured and re-settled in Asia Minor and the few that remained were assimilated. During the 11th and 12th centuries the return of stability resulted in the Greek peninsula benefiting from strong economic growth – much stronger than that of the Anatolian territories of the Empire. During that time, the Greek Orthodox Church was also instrumental in the spread of Greek ideas to the wider Orthodox world.
  Following the Fourth Crusade and the fall of Constantinople to the "Latins" in 1204 mainland Greece was split between the Greek Despotate of Epirus (a Byzantine successor state) and French rule (known as the Frankokratia), while some islands came under Venetian rule. The re-establishment of the Byzantine imperial capital in Constantinople in 1261 was accompanied by the empire's recovery of much of the Greek peninsula, although the Frankish Principality of Achaea in the Peloponnese and the rival Greek Despotate of Epirus in the north both remained important regional powers into the 14th century, while the islands remained largely under Genoese and Venetian control. During the Paleologi dynasty (1261–1453) a new era of Greek patriotism emerged accompanied by a turning back to ancient Greece.
  As such prominent personalities at the time also proposed changing the imperial title to "Emperor of the Hellenes", and, in late fourteenth century, the emperor was frequently referred to as the "Emperor of the Hellenes". Similarly, in several international treaties of that time the Byzantine emperor is styled as "Imperator Graecorum".
  In the 14th century, much of the Greek peninsula was lost by the Byzantine Empire at first to the Serbs and then to the Ottomans. By the beginning of the 15th century, the Ottoman advance meant that Byzantine territory in Greece was limited mainly
caption: Dome of Hagia Sophia, Thessaloniki (8th century), one of the 15 UNESCO's Paleochristian and Byzantine monuments of the city
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