The Powder River Basin is a geologic structural basin in southeast Montana and northeast Wyoming, about 120 miles (190 km) east to west and 200 miles (320 km) north to south, known for its extensive coal reserves. The former hunting grounds of the Oglala Lakota, the area is very sparsely populated and is known for its rolling grasslands and semiarid climate.

The Tongue River is a tributary of the Yellowstone River, approximately 265 mi (426 km) long, in the U.S. states of Wyoming and Montana. The Tongue rises in Wyoming in the Big Horn Mountains, flows generally northeast through northern Wyoming and southeastern Montana, and empties into the Yellowstone River at Miles City, Montana. Most of the course of the river is through the beautiful and varied landscapes of eastern Montana, including the Tongue River Canyon, the Tongue River breaks, the pine hills of southern Montana, and the buttes and grasslands that were formerly the home of vast migratory herds of American bison.