He was known as Panguan Tegin (泮官特勒), when raised to throne after his father's death.
According to one account he was killed by his brother, who for a time usurped the throne.
Another account suggested that Külüg Qaghan was poisoned by a khatun - E (葉), who happened to be a granddaughter of Pugu Huai'en.
His death happened just before Uyghurs suffered a heavy defeat under Grand Chancellor Inanchu Bilge (頡千逝斯) of Elter (𨁂跌) against Tibetans who were aided by Karluk Yabgu State ruler Alp Burguchan[2] who united Chigils, Bulaqs and Shatuo, near Beshbaliq.
As the result Yang Xigu (楊襲古) Commander of Beiting Protectorate committed suicide.