The term "Aigaion Pelagos" appears for the first time as an administrative circumscription in the early 8th century, when seals of several of its kommerkiarioi (customs officials) are attested.

[1][3][2] The theme of the Aegean Sea must have been created in 843: its governing strategos does not appear in the Taktikon Uspensky of 842/843, which still lists the droungarios, but he is elsewhere attested as being active at Lesbos in 843.

In the areas of the Dardanelles and the Propontis, however, the droungarios and later the strategos of the Aegean probably shared authority with the Count of the Opsician Theme, to whose jurisdiction these territories properly belonged.

The Count of the Opsicians probably retained authority over civil administration and local defence, while the Aegean theme was solely responsible for equipping ships and raising the men for fleets from these areas.

[6] According to Emperor Constantine VII Porphyrogennetos (r. 913–959), in the early 10th century the theme included Lesbos (the seat of the strategos), Lemnos, Imbros and Tenedos, Chios (later transferred to Samos), the Sporades and the Cyclades.