What is flat area west of the ural mountains

West Siberian Plain, Russian Zapadno-sibirskaya Ravnina, one of the world's largest regions of continuous flatland, central Russia. It occupies an area of nearly 1,200,000 square miles (3,000,000 square km) between the Ural Mountains in the west and the Yenisey River valley in the east.

Brand c i think that should be it

Don’t use up to much of them it leads to pollution