Cherson ( theme ) The Theme of Cherson ( , " thema Chersōnos " ) , originally and formally called the Klimata ( Greek : ) was a Byzantine theme ( a military - civilian province ) located in the southern Crimea , headquartered at Cherson . The theme was officially established in the early 830s and was an important centre of Black Sea commerce . Despite the destruction of the city of Cherson in the 980s , the theme recovered and prospered , enduring until it became a part of the Empire of Trebizond after the dissolution of the Byzantine Empire in 1204 . History . The region had been under Roman and later Byzantine imperial control until the early 8th century , but passed under Khazar control thereafter . Byzantine authority was re - established by Emperor Theophilos ( r . 829 – 842 ) , who displayed interest in the northern littoral of the Black Sea and especially his relations with the Khazars . Traditional scholarship dates the establishment of Cherson as the seat of a theme in ca . 833 / 834 , but more recent researchers have linked it with the Byzantine mission to construct the new Khazar capital at Sarkel in 839 , and identify Petronas Kamateros , the architect of Sarkel , as the theme ' s first governor ( " strategos " ) in 840 / 841 . The new province was at first called " ta Klimata " , " the regions / districts " , but due to the prominence of the capital Cherson , by ca . 860 it was known even in official documents as the " Theme of Cherson " . The province played an important role in Byzantine relations with the Khazars and later , after the Khazar Khaganate ' s collapse , with the Pechenegs and the Rus ' . It acted as a center for Byzantine diplomacy rather than military activity , since the military establishment in the theme seems to have been small and to have chiefly consisted of a locally - raised militia . Its weakness is underlined by the stipulation , in the Byzantine treaties with the Rus ' of 945 and 971 , of the latter ' s undertaking to defend it against the Volga Bulgars . Cherson prospered greatly during the 9th – 11th centuries as a centre of Black Sea commerce , despite the city ' s destruction by Vladimir of Kiev in 988 / 989 . The city recovered quickly : the city ' s fortifications were restored and extended to the harbour in the early 11th century . At the same time , possibly after the defeat of Georgius Tzul in 1016 , the theme had been extended over the eastern Crimea as well , as evidenced by the styling of a certain Leo Aliates as " " strategos " of Cherson and Sougdaia " in 1059 . The region however was lost again in the late 11th century to the Cumans . Almost nothing is known of Cherson in the 12th century , pointing to a rather tranquil period . Cherson and its province remained under Byzantine control until the dissolution of the Empire by the Fourth Crusade in 1204 , when they passed under the sovereignty of the breakaway Empire of Trebizond ( see Perateia ) . Administration . The Theme of Cherson appears to have been organized in typical fashion , with the full array of thematic officials , of whom a " tourmarches " of Gothia is known at the turn of the 11th century , as well as the ubiquitous fiscal and customs officials known as " kommerkiarioi " . The cities of the theme , however , appear to have retained considerable autonomy in their own government , as exemplified by Cherson itself , which was administered by the local magnates ( " archon tes " ) under a " proteuon " ( " the first " ) . Cherson also retained the right to issue its own coins , having resumed minting under Emperor Michael III ( r . 842 – 867 ) , and was for a long time the only provincial mint outside Constantinople . Its autonomy is also evidenced by the fact that the imperial government paid annual subsidies ( " pakta " ) to the city leaders in the fashion of allied rulers , and in the advice of Emperor Constantine Porphyrogennetos ( r . 913 – 959 ) in his " De Administrando Imperio " to the local " strategos " concerning the possibility of a revolt in the city : he was to cease payment of the subsidies and relocate to some other city in the theme . In the late 11th century , the theme was governed by a " katepano " .