sentences:  It has long been maintained by some scholars, including Chavannes, Uchida, Gao and Xue Zhongzeng that Tong Yabghu cannot be positively identified with Ziebel (or any Khazar ruler) and may actually have died as early as 626.These scholars point to discrepancies in the dates between Byzantine and Chinese sources and argue that definitively conflating Ziebel with Tong Yabghu is an exaggeration of the extant evidence.The latest research on this topic proves that they were right