Monument Valley (Navajo: Tsé Biiʼ Ndzisgaii, pronounced [tsʰépìːʔ ǹtsɪ̀skɑ̀ìː], meaning valley of the rocks) is a region of the Colorado Plateau characterized by a cluster of sandstone buttes, the largest reaching 1,000 ft (300 m) above the valley floor. The most famous butte formations are located in northeastern Arizona along the Utah–Arizona state line. The valley is a sacred area that lies within the territory of the Navajo Nation Reservation, the Native American people of the area. Monument Valley has been featured in many forms of media since the 1930s. Director John Ford used the location for a number of his Westerns; critic Keith Phipps wrote that "its five square miles [13 km2] have defined what decades of moviegoers think of when they imagine the American West".