river in west-central Russia, being a tributary of the Volga River. It rises in eastern Penza oblast (province) and flows north for 537 miles (864 km) to join the Volga River at Vasilsursk, near Nizhny Novgorod. The area of its drainage basin is 26,000 square miles (67,500 square km).

The river is navigable to Penza city. It receives the Inza, Alatyr, and Pyana rivers.