According to the "Old Book of Tang", Tong Yabghu's reign was once considered as the golden age of Western Göktürk Khaganate:"Tong Yehu Kaghan is a man of bravery and astuteness. He is good at art of war. Thus he controlled Tiele tribes to the north, confronted Persia to the west, connected with Kasmira (nowadays Kashmir) to the south. All countries are subjected to him. He controlled ten thousands of men with arrow and bow, establishing his power over the western region. He occupied the land of Wusun and moved his tent to Qianquan north of Tashkent. All of the princes of western region assumed the Turk office of Jielifa. Tong Yehu Kaghan also sent a Tutun to monitor them for imposition. The power of Western Turks had never reached such a state before"."