The Protohistoric period in the Greater Southwest was a time when native peoples and institutions struggled to hold off an alien cultural system. The incoming Spaniards were ideologically aggressive and superior in political organization and in military and economic power. In addition, they introduced European diseases, powerful, if inadvertent, allies. It was population loss, resulting from disease, that allowed the Jesuits in the early 17th century to conquer the northern and central Sonoran area when Spanish arms had failed to do so in the 16th. The Pueblo region to the north also was ravaged by disease, but this effect seemed to have been delayed. Whereas the Sonoran Serrana peoples underwent some sort of demographic collapse in the half century between Ibarra (1565) and the first contact of the Jesuits (around 1615), most Pueblos were still functioning reasonably well until the great population slump of the 17th century. We know less about the Desert and Colorado provinces and that of La Junta, but the large populations found by Kino and his fellow Jesuits in the Gila-Salt valleys had presumably been larger still in Coronado's day. The same is likely true for the Lower Colorado Yuman-speaking Indians. In the Colorado River Valley there were vigorous populations very much involved in the Greater Southwest trade network. Unfortunately, not enough systematic archaeology had been done on the Hakataya ancestors of the 16th-century Yuman peoples to make definitive statements as to their influence in the centuries that led up to the Protohistoric period (see Schroeder 1979:106-107). The Jornada Mogollon Indians expanded eastward along the Rio Grande to La Junta de los Rios, establishing themselves by A.D. 1400 at La Junta and in the Redford Valley to the east (Kelley 1952:361). At La Junta, 229however, even by earliest formal contact in 1581, there already had been considerable Spanish influence in the lower Conchos region and population may have been on the decline.