The Greater Southwest has long been occupied by hunter-gatherers and agricultural people. This area, identified with the current states of Colorado, Arizona, New Mexico, Utah, and Nevada in the western United States, and the states of Sonora and Chihuahua in northern Mexico, has seen successive prehistoric cultural traditions since approximately 12,000 years ago. An often quoted statement from Erik Reed (1964) defined the Greater Southwest culture area as extending north to south from Durango, Mexico to Durango, Colorado and east to west from Las Vegas, Nevada to Las Vegas, New Mexico. Other names sometimes used to define the region include "American Southwest", "North Mexico", "Chichimeca", and "Oasisamerica/Aridoamerica".