Within a short period after the year of 1556, a struggle burst out between Küçüm and Yadigar and the city of "Isker" over the Irtish River and the domination of the Western Sibir Khanate got under the dominion of Küçüm.
Küçüm Khan and the Turkish (Tatar) tribes on the banks of Irtish were the members of the religion of Shamanism and they were faithful to their ancient traditions. Küçüm Khan applied to Bokhara Khan, Abdullah Khan and requested from him to send Muslim teachers to the city of Isker in order to teach the religion of Islam. Upon this event, some of the religious scholars and sheikhs came from Bokhara and they helped to the dissemination of the religion of Islam. Some of the Turkish tribes and particularly those that were near to the Irtish and Obi Rivers and the Altay Mountains had maintained their old religion of Shamanism. The people of the city of Isker and the environs could reach to a higher level of civilisation through the efforts of Küçüm Khan. However, this beneficial activities of the khan were impeded by the Russian attacks and the khan had to fight with them in order to defend his country from the Russians instead of the diffusion of the civilisation.