Bucellarian Theme The Bucellarian Theme ( , " Boukellarion thema " ) , more properly known as the Theme of the Bucellarians ( , " thema Boukellariōn " ) was a Byzantine theme ( a military - civilian province ) in northern Asia Minor ( modern Turkey ) . It was created around the middle of the 8th century , comprising most of the ancient region of Paphlagonia and parts of Galatia and Phrygia . History . The theme was established sometime after 743 and before 767 by the Emperor Constantine V ( r . 741 – 775 ) , following the suppression of the revolt of Artabasdos , the Count of the " Opsikion " . The new theme , along with that of the " Optimatoi " was split off from the " Opsikion " as formed part of the Emperor ' s policy to reduce the latter ' s power . The name of the theme derives from the late Roman " Bucellarii " , elite cavalry troops of Gothic or Roman origin , often found as privately recruited bodyguard troops . By the early 7th century , they formed an elite division in the " Opsikion " field force , coming under a " domestikos " before their elevation to a full theme . The " strategos " of the Bucellarians is attested for the first time in 767 , providing a " terminus ante quem " for its creation . His headquarters were at Ancyra , the former capital of " Opsikion " , and he belonged to the second tier of " strategoi " with an annual salary of 30 pounds of gold . According to Arab geographers , he commanded some 8 , 000 troops . The court ranks of the Bucellarian " strategoi " ranged from the mid - level " spatharios " to the higher " protospatharios " , with a single occurrence of the more exalted " patrikios " in the 10th century . Claudiopolis is the only attested base of one of the theme ' s " tourma i " . Despite it being originally a cavalry theme ( " thema kaballarikon " ) , the Bucellarians , as well as the later Paphlagonian theme , also included a small fleet , active in the Black Sea . The " " katepano " of the Bucellarians and the Paphlagonians " , whose seal is attested in the 10th century , was the commander of this naval contingent . However , evidence points to the fact that the 10th - century fleet was composed of merchantmen and transport ships , not warships . Initially , the theme stretched from the Black Sea coast to the central Anatolian plateau , bordering the " Optimatoi " and the rump of the " Opsikion " in the west , the Anatolic theme in the south , and the Armeniac theme in the east . In the 9th century , however , probably c . 820 , the northeastern half of the theme was detached and formed , perhaps with some territory from the Armeniac theme , the new theme of Paphlagonia . Its extent was further reduced under Emperor Leo VI the Wise ( r . 886 – 912 ) , when eight southern and southeastern " banda " were removed to form part of the new themes of Cappadocia ( around Lake Tuz ) and Charsianon ( east of the Halys River ) . In the 9th century , it comprised two towns and thirteen fortresses , while five towns are recorded in the 10th century . The theme survived until it was overrun by the Seljuk Turks following the Battle of Manzikert in 1071 . The name " Boukellariōn " , however , survived as a geographical designation in Byzantine sources up until 1263 .