These Mirzas organized loosely knit dominions, which were all under the nominal authority of the Khan of Tyumen and Sibir.
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Islam was the professed religion of the Sibir Khanate; it was the religion of the ruling Khan of Tyumen and Sibir.
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Mirzas also led the warriors of the Khanate of Sibir into battle and owed nominal allegiance to the Khan of Tyumen and Sibir.
The Khanate of Sibir and the town of Tyumen were founded by Taibuga probably some time between 1405 and 1428.