Editing Sarkel (section)

==Construction==
Sarkel was built to protect the north-western border of the Khazar state in 833. The Khazars asked their ally, [[Byzantine Empire|Byzantine]] emperor [[Theophilos (emperor)|Theophilus]], for engineers to build a fortified capital, and Theophilus sent his chief engineer [[Petronas Kamateros]]. In recompense for these services, the Khazar [[khagan]] ceded [[Chersonesos Taurica|Chersonesos]] and some other Crimean dependencies to Byzantium.

Historians have been unable to determine why such a strong fortress was built on the Don. They generally assert that the costly construction must have been due to the rise of a strong regional power that posed a threat to the Khazars. [[Alexander Vasiliev (historian)|Alexander Vasiliev]] and [[George Vernadsky]], among others, argue that Sarkel was built to defend a vital [[portage]] between the Don and the Volga from the [[Rus' Khaganate]]. Other historians believe this polity was situated many hundred miles to the north. Another nascent power, the Hungarians, was not particularly threatening to the Khazars as long as they paid tribute to the khagan.

[[Constantine Porphyrogenitus]] records in his work [[De Administrando Imperio]] that the Khazars asked the Emperor Theophilos to have the fortress of Sarkel built for them. His record is connected to the Hungarians on the basis that the new fortress must have become necessary because of the appearance of a new enemy of the Khazars, and other peoples could not be taken into account as the Khazars’ enemies at that time. In the 10th century, a Persian explorer and geographer [[Ahmad ibn Rustah]] mentioned that the Khazars entrenched themselves against the attacks of the Hungarians.