Complex sentence: Located on the Great Plains, just north of the Nebraska Sandhills, Rosebud Indian Reservation has large areas of Ponderosa Pine forest scattered in its grasslands, and deep valleys are defined by steep hills and ravines, often with lakes dotting the deeper valleys.
Split into simpler sentences: Located on the Great Plains, just north of the Nebraska Sandhills, Rosebud Indian Reservation has large areas of Ponderosa Pine forest scattered in its grasslands. Deep valleys are defined by steep hills and ravines, often with lakes dotting the deeper valleys.