Tobol

The Tobol (, "Tobyl") is a river in Western Siberia (in Kazakhstan and Russia) and the main (left) tributary of the Irtysh. Its length is , and the area of its drainage basin is .
History.
The Tobol River was one of the four important rivers of the Siberia Khanate. In 1428 the khan was killed in a battle with the forces of Abu'l-Khayr Khan at the Battle of Tobol.
In the 16th century, the Tobol was the eastern terminus of the portage route leading westward to the rivers Vishera and Kama.
Main tributaries.
The largest tributaries of the Tobol are, from source to mouth: