The theme of Strymon (Greek θέμα Στρυμόνος ) was a Byzantine theme, whose capital was Serres. After his emergence in the 9th century, it went through a turbulent time in which it was regularly merged with other topics and separated again.
The topic covered the area between the Strymon and Nestos, the Rhodope Mountains in the north and the Aegean Sea in the south. The area was strategically important because it guarded the mountain passes to the Slav -dominated interior of the Balkan peninsula, and because it was crossed by the Via Egnatia important that the Byzantine Thrace linked with Thessaloniki, the second largest city of the Byzantine Empire. From the late 7th century, the area was mainly inhabited by Slavs, who provided the majority of the population until the 11th century. The main cities of the topic were Serres, Philippi, Christoupolis and Chrysopolis, it could originally the cities of Xanthi and Mosynopolis east of the Strymon have included.
In the 8th century was a Strymon Kleisoura the theme of Macedonia. The exact date of his elevation to the autonomous subject is unknown, but is probably in the first half of the 9th century. A passage in the work of Theophanes of 809 could mean the existence of the subject even at this stage, it is found to have not disclosed in Taktikon Uspensky 842 of the strategos of the Strymon, appear for the first time in 899 Kletorologion, but there are a number of seals with titles Archontes and strategoi of Strymon from the second half of the 9th century known. At the same time the Bishop of Serres was raised at the same time as archbishop, which could indicate the collection of Serres to Topic capital.
In the 10th century the subject was divided into two parts: the actual (old ) Strymon Chryseuba or Chrysaba (Greek: Χρυσεύβα / Χρυσάβα ) and New Strymon (Greek: Νέος Στρυμών ). The latter has been preserved only by the Taktikon Oikonomides of about 975. It was either the eastern part of the old theme east of the Nestos, or an area in the north of the river Strymon, that after Emperor John Tzimiskes (reigned 969-976 ) conquest of Bulgaria was 971 fell to the Reich. Towards the end of the 10th century the theme of Strymon was apparently united with the theme of Thessalonica.
The Themma existed until the dissolution of the Byzantine Empire after the Fourth Crusade, after which it became part of the short-lived Kingdom of Thessalonica. In 1246, the theme was restored after that area from Nicaean Emperor John III. had been recaptured. In the 14th century it was again united with the theme of Thessalonike, it also appears as the theme of " Serres and Strymon ." Finally the issue was resolved after a brief Serbian conquest during a Byzantine civil war.