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 the Humahuaca quebrada encountered competition from two main roads to the Pacific. These followed in part ancient trails by which the Indians of the Puna de Atacama and its high quebradas brought down their salt, goatskins, and woven fabrics to barter for the produce of the warmer valleys. Thence

. 61—Shepherd's stone hut at the crest of the Cuesta del Obispo above the limit of a favorable water supply and of the growth of cereals.

they crossed the Atacama Desert to Copiapé and Cobija (succeeded later by Antofagasta) respectively. The southern route passed through the Calchaqui valley, creating in Molinos a commercial station of importance, and thence, skirting the southern salars of the puna, entered Chile by way of the passes of San Francisco and Tres Cruces (Fig. 87, p. 259). The more northerly route passed through the ancient copper mining site of San Antonio de los Cobres, the stretch of ‘‘ Despoblado”’ to the oasis of San Pedro de Atacama, and thence westward