Editing Thessaly (section)

===Byzantine period===
{{further|Byzantine Greece}}
[[File:59. Βυζαντινό ΚάστροΤρικάλων, παλιά πόλη Βαρούσι GR-E44-0002.jpg|thumb|Part of the Byzantine [[Trikala Castle|castle]] of Trikala]]
[[File:MakElassona04.jpg|thumb|180px|View of the [[Panagia Olympiotissa Monastery]] in [[Elassona]]]]

Thessaly remained part of the East Roman "Byzantine" Empire after the collapse of Roman power in the west, and subsequently suffered many invasions, such as by the Slavic tribe of the [[Belegezites]] in the 7th century AD.<ref>{{cite book |title=History of Humanity: From the seventh century B.C. to the seventh century A.D. |url=https://books.google.com/books?id=WGUz01yBumEC&pg=PA252 |date=January 1, 1996 |publisher=[[UNESCO]]|isbn=978-92-3-102812-0 |page=252 |first1=Sigfried J. |last1=de Laet |first2=Joachim |last2=Herrmann |chapter=The Invasion of Slaves and Avars (c. 568 to 626) |chapter-url=https://books.google.com/books?id=WGUz01yBumEC&pg=PA252 |editor-last=Tapkova-Zaimova |editor-first=Vasilka}}</ref> The [[Avars (Caucasus)|Avars]] had arrived in Europe in the late 550s.<ref name="Fine83">Fine, John V. A., Jr. 1983, ''Early Medieval Balkans: A Critical Survey From the Sixth to the Late Twelfth Century,'' University of Michigan Press {{ISBN|9780472100255}}</ref>{{rp|29}}  They asserted their authority over many Slavs, who were divided into numerous petty tribes.{{sfn|Fine|1991|p=30}}  Many Slavs were galvanized into an effective infantry force, by the Avars. In the 7th century the Avar-Slav alliance began to raid the Byzantine Empire, [[Siege of Thessalonica (617)|laying siege]] to Thessalonica and even the imperial capital [[First Siege of Constantinople|Constantinople]] itself.

By the 8th century, [[Slavs]] had occupied most of the Balkans from Austria to the Peloponnese, and from the Adriatic to the Black seas, with the exception of the coastal areas and certain mountainous regions of the Greek peninsula.{{sfn|Fine|1991|p=36}}  Relations between the Slavs and Greeks were probably peaceful apart from the (supposed) initial settlement and intermittent uprisings.{{sfn|Fine|1991|p=63}} Being agriculturalists, the Slavs probably traded with the Greeks inside towns.{{sfn|Fine|1991|p=61}} It is likely that the re-[[Hellenization]] had already begun by way of this contact. This process would be completed by a newly reinvigorated Byzantine Empire.

With the abatement of [[Arab-Byzantine Wars]], the Byzantine Empire began to consolidate its power in those areas of mainland Greece occupied by Proto-Slavic tribes. Following the campaigns of the Byzantine general [[Staurakios (eunuch)|Staurakios]] in 782–783, the Byzantine Empire recovered Thessaly, taking many Slavs as prisoners.{{sfn|Fine|1991|p=79}} Apart from military expeditions against Slavs, the re-Hellenization process begun under Nicephorus I involved (often forcible) transfer of peoples.{{sfn|Fine|1991|p=81}}

Many Slavs were moved to other parts of the empire such as Anatolia and made to serve in the military.{{sfn|Fine|1991|p=66}} In return, many Greeks from Sicily and Asia Minor were brought to the interior of Greece, to increase the number of defenders at the Emperor's disposal and dilute the concentration of Slavs.{{sfn|Fine|1991|p=82}}