The Turks, after many rebuffs, consented to a suggestion made by their mercantile subjects of the Soghd, and in 568 sent an embassy to Constantinople to form an alliance with the Byzantines and commence the silk trade directly with them, bypassing the Persian middlemen.
They accompanied him some way on his march against Persia, passing through Talas or Hazrat-e Turkestan in the Syr Daria valley, where Xuanzang, on his way from China to India sixty years later, met with another of Dizabul's successors.
George hurried on by the shortest route, "desert and waterless", apparently the steppes north of the Black Sea, while his superior, moving more slowly, marched twelve days by the sandy shores of the lagoon.
He crossed the Emba, Ural, Volga, and Kuban (where 4000 Persians vainly lay in ambush to stop him), and passing round the western end of the Caucasus, arrived safely at Trebizond and Constantinople.
[1] For several years this Turkic alliance subsisted, while close trade was maintained between Central Asia and Byzantium (when another Roman envoy, one Valentinos, went on his embassy in 575 he took back with him 106 Turks who had been visiting Byzantine lands) but from 579 this friendship rapidly began to cool.