The Irtysh is a river in Russia, China, and Kazakhstan. It is the chief tributary of the Ob and is also the longest tributary river in the world.

Omsk is the administrative center and largest city of Omsk Oblast, Russia. It is situated in southwestern Siberia and has a population of over 1.1 million. Omsk is the third largest city in Siberia after Novosibirsk and Krasnoyarsk, and the twelfth-largest city in Russia. It is an important transport node, serving as a train station for the Trans-Siberian Railway and as a staging post for the Irtysh River.