A map of the Irtysh river basin
|Country||Mongolia, China, Kazakhstan, Russia|
|Main source||Altay Mountains|
|River mouth||Ob River|
|Length||4,248 km (2,640 mi)|
|Basin size||1,643,000 km2 (634,000 sq mi)|
The Irtysh River (Russian: Иртыш; Kazakh: Ertis / Ертiс; Chinese: 额尔齐斯河 / É'ěrqísī hé; Mongolian: Эрчис мөрөн, "Twirl"; Tatar: Cyrillic Иртеш, Latin İrteş) is a river in Siberia and Kazakhstan. It is the main tributary of the Ob River. The main tributary of the Irtysh is the Tobol River. The Ob-Irtysh forms a major drainage basin in Asia, and covers most of Western Siberia and the Altay Mountains.