Sy Yabghu Qaghan was a khagan in the Western Turkic Khaganate between 631 and 633 or 630 and 632.630 from Christoph Baumer, History of Central Asia,2,205. Si Yabghu is from Baumer, possibly a confusion of two words. His full title was Yǐpí (shā)bōluō sì yèhù kèhán (乙毗(沙)钵罗肆叶护可汗; reconstructed Old Turkic: *IrbisGumilyiv, L. N. Drevnie Tyurki Chapter 33 (in Russian) ~ YelbiZuev, Yu. A., Rannie tyurki: ocherki istorii i ideologii, Dajk-Press, Almaty, 2004, p. 182 (in Russian) (Ysh)bara Sir Yabghu Khagan); personal name: Ashina Xili (阿史那咥力).
Reign He was raised to throne with the support of Nushibi tribes and his cousin Nishu. However he was no more successful than his predecessor. He couldn't control the Xueyantuo and he executed so many people that even his former partisan Nishu planned to escape. After losing his supporters and prestige he escaped to south in 633. Nishu succeeded him as Duolu Qaghan.
Later years He tried to raid the city of Balkh (now in north Afghanistan), but was killed in the clash.L.M.Gümilev :Eski Türkler, tr:Ahsen Batur, Selenge yayınları, İstanbul, 2002, , , pp.265-266
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