Canyon de Chelly National Monument [De Chelly, Sp. corruption of Navajo Tsegi = rock canyon], 83,840 acres (33,955 hectares), NE Ariz.; est. 1931. The area contains the ruins of several hundred prehistoric Native American villages, most of them built A.D. 350-1300. The spectacular cliff dwellings include Mummy Cave, with a three-story tower house. Artifacts have been found, and there are numerous pictographs in rock shelters and on cliff faces. The earliest people living in the region were the Basket Makers, predecessors of the Pueblo. The Navajo came to the canyon c.1700, and it became their chief stronghold. In 1805 a Spanish expedition fought the Navajo in a rock shelter (dubbed Massacre Cave) in Canyon del Muerto (site of a prehistoric burial ground). In 1864 a U.S. cavalry force under Kit Carson engaged the Navajo in Canyon de Chelly. See National Parks and Monuments, table.