George Pisidia (Γεώργιος Πισίδης, (of Pisida in Latin) aka The Pisidian) was a Byzantine deacon and poet, born in… Pisidia. He flourished during the 7th century AD.
From his poems we learn he was a Pisidian by birth, and a friend of Patriarch Sergius I of Constantinople and the Emperor Heraclius. His earliest work, in three cantos, is De expeditione Heraclii imperatoris contra Persas, libri tres on Heraclius’ campaign against the Persians in 622. His second work was Avarica (or Bellum Avaricum), an account of the Avar attack on Constantinople in 626. Then came the Heraclias (or De extremo Chosroae Persarum regis excidio), a general survey of the exploits of Emperor Heraclius both at home and abroad down to the final overthrow of the Persian Chosroes in 627. Some of his works may have been used by Theophanes the Confessor as a basis for his Chronographia.
Of interest to us, both the Avarica and the Heraclias contain some very early references to the Slavs (referring to them as Sthlawos).
Avarica
(or Bellum Avaricum)
written in 626
“Truly a tempest of our enemies came at us like the sea’s countless waves, throwing the sands of different barbarian tribes; For that summer an ominous wind sent forth onto our heads from all of Thrace a terrible snowstorm from many clouds gathered…”
“…Not one of these struggles was easy, as [they] all spattered [among us], [first] coming [as each was] from a variety of different causes intertwined together. For the Slavs with the Huns and the Scythian* with the Bulgar, and from the other side a Medes** also with the Scythian conspiring, [each] different from one another in language and blood, yet though far from one another, from afar coming together, they raised one sword against us, demanding that we should fatuously take their deceit for steadfast fidelity…”
* Huns and Scythians meaning Avars.
** Medes meaning Persians.
“…And the barbarian [i.e., the Avar khagan] put his hordes of Slavs together with Bulgars onto ships, for he had canoes hallowed from tree trunks, and added a sea battle to that on land…”
Heraclias
(or De extremo Chosroae Persarum regis excidio)
written circa 627-629
“…And from beyond, from Thrace, clouds gathered again bringing us the thunder of war; and from one side the Scythian Charybdis silently went about marauding, and from the other, the Slavs like wolves ran out to sting us on land and sea. The sea waves mixed with their blood after the battle seemed red to the eye, so much that this sight seemed like Perseus’ Gorgon [Medusa] terrible, and the whole world plunged in the depths…”