What are the rugged hills in North Dakota called?

The rugged hills in North Dakota are called the Badlands. They are located in the southwestern part of the state and are characterized by steep cliffs, canyons, and buttes. The Badlands were formed by millions of years of erosion from the Little Missouri River and its tributaries. The area is also known for its unique plant and animal life, including several species of cacti and sagebrush.