Agriculture in the prehistoric Southwest
After the Hohokam disappeared, Spanish explorers of the 16th century noted the use of canal irrigation in only two areas of the Southwest: eastern Sonora, primarily practiced by the Opata and Lower Pima, and among the Pueblos of northern New Mexico. Irrigation by the Opata and Pueblos had different objectives. In Sonora, with a long growing season, two crops of maize a year were grown in river valleys. The spring crop during the dry season was dependent upon irrigation; the summer and fall crop during the rainy season utilized irrigation to supplement rainfall. The necessity of irrigation probably required a high level of social organization. In New Mexico, with only one crop of maize per year possible, irrigation was supplemental and the lesser dependence on irrigation implies less social organization than in Sonora.
Ejea de los Caballeros
Rivas and Farasdués are two historic villages that have been dependencies of Ejea for decades. The other six centres were built in the nineteen fifties and sixties in order to settle inhabitants and farmers to grow irrigation crops because of the building of Yesa reservoir and Bardenas irrigation channel that brought water to this villages, among others (Sádaba, Tauste and others).