The Muʿizz al-ansāb and the Tawārīḫ-i guzīdah-i nuṣrat-nāmah give his descent as follows: Chinggis Khan - Jochi - Shiban - Bahadur - Jochi-Buqa - Bādāqūl - Ming-Tīmūr - Īl-Bīk - Qāghān-Bīk.
According to Ibn Khaldun, Qāghān Beg (whom he calls Karī Khān), who may have been present with his father at Sarai, fled to his family lands east of the Ural.
Accordingly, when Qāghān Beg instructed the two grand princes to make the governor of Bolghar, Asan (Ḥasan), submit to his authority in 1376, they readily set out on a campaign.
However, before the army of ʿArab Shāh could engage with them, and in the temporary absence of the Muscovites, Mamai succeeded in surprising and routing the Nižegorodians at the P'jana river, and proceeded to sack and burn Nižnij Novgorod in 1377.
[5] Unwilling to miss the opportunity to inflict his intended vengeance on the Russians and plunder them, or to allow Mamai to reassert his suzerainty over them,ʿArab Shāh proceeded with his campaign.
Taking advantage of the confused and weakened state of the Russian princes, he successfully raided and plundered the territories of Nižnij Novgorod and Rjazan', even capturing the latter's capital in the autumn of 1377.
[6] According to the Čingīz-Nāmah, the Tuqa-Timurid prince Tokhtamysh sought refuge with Qāghān Beg from his cousin, the aggressive Urus Khan, a common enemy.