Maidu , also Northeastern Maidu or Mountain Maidu, is an extinct Maiduan language spoken by Maidu peoples traditionally in the mountains east and south of Lassen Peak in the American River and Feather River river drainages. These river regions include such valleys in the northern Sierra Nevada mountains of California as: Indian Valley, American Valley, Butte Valley, and Big Meadows. Maidu may also refer to the related Konkow and Nisenan languages.