[citation needed] From 576 through 583 CE, Tardu fought with the Byzantines, but, instead of himself, he appointed as head of the campaign his cousin Böri Shad, whose possessions were in the North Caucasus.
[1][clarification needed] According to Movses Kagankatvatsi, Böri Shad was a 7th-century Göktürk prince and an ishad or general in the army of the Western Turkic Khaganate.
Under Böri Shad's command the Khazars sacked many cities in Caucasian Albania and attempted to establish a firm foothold in Transcaucasia.
[3] Following Tung Yabghu's instructions, Böri Shad suggested to the Persian satrap of Aghvania and to Catholicos Viro that they should acknowledge the Khagan as their overlord.
In April 630 Böri Shad took advantage of dynastic disorders in the Sassanid Empire and dispatched Chorpan Tarkhan to conquer Armenia.