It was established as a theme in 911 and endured until its fall to the Seljuk Turks in the aftermath of the Battle of Manzikert in 1071.

[2] In 908, Sebasteia appears for the first time as a distinct fortified frontier district (kleisoura), and by 911 it had been raised to the status of a full theme.

[4] The theme comprised the entirety of the Byzantine frontier regions along the middle course of the northern Euphrates.

Both districts were briefly raised to kleisourai—Larissa in c. 908–911 and Amara/Abara under Romanos I Lekapenos—and became the seat of independent strategoi by 975, leading to the theme's progressive diminution and decline in significance.

[1][6] After 1019/1021, Sebasteia and adjoining lands were given as a fief to the Armenian Seneqerim Ardzruni, in exchange for the cession to the Empire of his kingdom of Vaspurakan.