About T'ung Yabghu Ziebal, Khagan of the Khazars
KAGAN ZIEBEL AND THE BYZANTINES
The Byzantines and the Khazars had a long period of relations, starting in the seventh century.
The Byzantine emperor Heraclius formed a military alliance with the Khazars in 626 as a bloc against the Persians. The alliance came about as the result of a meeting in 626 at Tbilisi between Heraclius and Ziebel, the kagan of the western Turkish Empire (including Khazaria), following a Khazar - Turkic expedition to Azerbaijan. When he was offered marriage to Heraclius' daughter, named Epiphania or Eudocia, Ziebel offered forty thousand men to serve in the Byzantine army as an auxiliary force. Although Ziebel was engaged to Eudocia, he died circa 630 in an internal dispute.
Activities then shifted from Persia to the south Caucasus. Kagan Ziebel's forty thousand horsemen invaded and plundered Tbilisi in 628 or 629 and were immensely successful. The Khazars took many prisoners and treasures in their conquest of Tbilisi. Viroy, a Christian church leader (catholicos), met the Khazar warriors at their victory camp and observed them holding a celebratory fiest consisting of wine, camel milk, and cold meat dipped in salty water.
The Khazars also occupied the Qabala region (east of Shakki, in ancient Albania and present day northern Azerbaijan) in the late 620s. The Khazars gave the Caucasian Albanians an ultimatum: Either surrender and become vassals to the Khazar state or males over fifteen years of age would be slaughtered and women and children would become enslaved. The Caucasian Albanians were able to prevent their demise by handing over a large fortune to the Khazars' army commander. All of the Caucasian Albanian prisoners were subsequently released by the Khazars. Still, territories in Caucasian Albania, as well as Derbent and Lp'ink, became incorporated into the Khazar realm. People living along the Kur and Araxes Rivers were taxed by the Khazars around 629 - 630. Similarly, in 629 the Khazar kagan imposed taxes on the people of Tbilisi and directed Khazarian government officials to control artwork, metal production, fishing, and commercial activities. A Khazar army invaded Armenia and successfully fought back against Persian counterattacks. Thus, the Khazars ruled Georgia, Caucasian Albania, and part of Armenia during this time, but the Byzantines held onto most of Armenia.
Around 630, the western Turkish kagan was overthrown after internal disputes. As a consequence, the Khazars' dominance over the southern Caucasus ended. The Persians regained control over Armenia and Azerbaijan by 632. Furthermore, upon Ziebel's death, Emperor Heraclius lost his alliance with Khazaria. Thus, this initial Byzantine - Khazar alliance lasted only about four years. Two other Byzantine - Khazar royal marital engagements would follow in successive years.
"The Jews of Khazaria" / Kevin Allan Brook: 1999 / Jason Aronson, Inc. -- pp. 166 - 168