B. The Spanish "Epidemic Region"
The existence of a "New Spain Epidemic Region" corresponding to the area under Spanish sover-eignty through which infections were spread by the movement of Spanish officials and citizens, Indian traders, etc., dates from the first introduction of smallpox into Mexico in 1520 by a Negro in the Narvaez expedition. The size of this epidemic region thereafter depended upon the area which had been brought under Spanish political dominance plus bordering regions in close contact with that subjugated area.
So far as the northern Piman Indians are concerned, they had evidently formed a part of the New Spain epidemic region for many years prior to the measles epidemic of 1729. While there were permanent Spanish outposts with Europeans in residence only south and east of northern Piman territory, Jesuit priests with military escorts had made periodic visitations 19northward and westward from those outposts for many years. Most recently, Father Campos from Mission San Ignacio had led the northward probes of Spanish power on the western flank, and Father Ignacio Arzeo in charge of the fort of Fronteras led the eastern probes (Alegre 1841:III:230). Earlier the northern probes had been led by Father Eusebio Francisco Kino from his post at Mission Nuestra Señora de los Dólores de Cosari. Kino's first northward exploration through the Santa Cruz River Valley had come as early as 1691 (Bolton 1948:I:119).
Even before Kino established the first mission among the northern Pimas in 1687, these Indians had established sufficient contact with Spaniards and other missionized Indians to have been in all probability a part of the epidemic region. Northern Piman parents carried infants to older Jesuit missions to have them baptized long before Kino reached their own country. The mission at Cucurpe was one major point of contact between the northern Pimans and the Spaniards prior to 1687. Another important early contact centre was the visita of Arispe mission at Bacuachi, where many Piman-speaking Indians had come to be baptized, settled in the town for a period, and left again prior to the year 1678 (Ortiz Zapata 1678:16v). The periodic residence of Piman Indians as far southeast as Bacuachi when it was already a mission visita certainly linked the northern Pimans up with the Spanish epidemic region.
This pattern of northern Piman visits to Spanish outposts southeast of their territory continued into the 1720's when 20documentation of epidemic effects becomes reliable for the Piman country. Not only were the Indians visiting the Jesuit missionaries in the upper San Miguel and Magdalena river valleys, but also the secular priest serving as chaplain of the Royal Fort at Fronteras, to ask him to baptize their children (Alegre 1841:III:230).
Even earlier, Franciscan missionaries brought south from New Mexico had reached the southern settlements of the northern Pimans in 1645 (Schroeder 1956:102-103). Spanish civil authorities were operating in central Sonora by that time (Alegre 1841:II:243) so there is every likelihood that the paths of epidemic infection had been opened to the northern Piman settlements by that time. In fact, it is possible that the northern Pimans were brought into this epidemic region even before, since Piman mothers took infants to the Jesuit missions on the Sonora River prior to the arrival of the Franciscans (ibid., II:265). The central Mexican epidemic region had expanded to the borders of southern Sonora long before, and once the military barrier of the Yaqui tribe was bypassed by acceptance of Jesuit missionaries by that tribe in 1617, the coastal desert trails were at least sufficiently open to travel to enable spread of infections northward.
Somewhat earlier the settlement of the Rio Grande River Valley in north central New Mexico by Juan de Oñate in 1598 had established a reservoir of infection to the east of northern Piman territory, especially as the annual supply caravans from the City of Mexico renewed the supply of germs in 21New Mexico and the outposts established along the Cordillera to protect its supply line. In fact, the northern Pimans were oriented much more toward these outposts such as Janos and Corodéguachi prior to the arrival of Father Kino than they were to the southern Sonoran settlements. The Cordillera forts were the nearest centres of Spanish military power, and it was from them that the northern Pimans were regulated for many years prior to their missionization (Hackett 1926:II:231). There was even direct trade between the New Mexican Spaniards and the northern Pimans as already mentioned (Bolton 1948:II:257) but that was probably initiated after the Franciscan missionization attempt in 1645 and it terminated prior to the arrival of Jesuit missionaries among the northern Pimans in 1687 and later years.