Georgius Tzul was a Khazar warlord against whom the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 and Mstislav of Tmutarakan launched a joint expedition in 1016.
He appears only in the account of the Byzantine court historians Kedrenos

Kedrenos

George Kedrenos or Cedrenus was a Byzantine historian. In the 1050s he compiled A concise history of the world, which spanned the time from the biblical account of creation to his own day. Kedrenos is one of the few sources that discuss Khazar polities in existence after the sack of Atil in 969...

 and John Skylitzes

John Skylitzes

John Skylitzes, latinized as Ioannes Scylitzes was a Greek historian of the late 11th century. He was born in the beginning of 1040's and died after 1101.- Life :Very little is known about his life...

, who place him at Kerch

Kerch

Kerch is a city on the Kerch Peninsula of eastern Crimea, an important industrial, transport and tourist centre of Ukraine. Kerch, founded 2600 years ago, is considered as one of the most ancient cities in Ukraine.-Ancient times:...

 and calls him "khagan

Khagan

Khagan or qagan , alternatively spelled kagan, khaghan, qaghan, or chagan, is a title of imperial rank in the Mongolian and Turkic languages equal to the status of emperor and someone who rules a khaganate...

" (the title of the Khazar emperors). Kedrenos states that he was captured by the expeditionary force but does not relate his ultimate fate. Inscriptions and other references exist referring to a Tzul or Tsal clan in Crimea

Crimea

Crimea , or the Autonomous Republic of Crimea , is a sub-national unit, an autonomous republic, of Ukraine. It is located on the northern coast of the Black Sea, occupying a peninsula of the same name...

 during this period; presumably he was a member although the relationship of that family to the original ruling dynasty of Khazaria is unknown. Almost nothing else about him, including the extent of his holdings, is known.

Despite the fact that earlier writers maintained that the Khazar khagan was required to adhere to Judaism

Judaism

Judaism ) is the "religion, philosophy, and way of life" of the Jewish people...

, Georgius is a Christian

Christian

A Christian is a person who adheres to Christianity, an Abrahamic, monotheistic religion based on the life and teachings of Jesus of Nazareth as recorded in the Canonical gospels and the letters of the New Testament...

 name. Whether Georgius Tzul was himself a Christian, a Jew or shamanist with an unusual Greek name, or whether the name is merely a Byzantine attempt to transliterate a Turkic or Hebrew name, is unknown.

It is worth noting that Byzantine campaigns occurred roughly during this period against the Georgians

Georgia (country)

Georgia is a sovereign state in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded to the west by the Black Sea, to the north by Russia, to the southwest by Turkey, to the south by Armenia, and to the southeast by Azerbaijan. The capital of...

 and Bulgars

Bulgars

The Bulgars were a semi-nomadic who flourished in the Pontic Steppe and the Volga basin in the 7th century.The Bulgars emerge after the collapse of the Hunnic Empire in the 5th century....

, suggesting a concerted effort to re-establish Byzantine dominance in the Black Sea

Black Sea

The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...

region.