384 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



homeland in Arizona now are known. The techniques employed in 

 discovering and recording a major part of the story of the Hohokam 

 peoples, after the lapse of centuries, not only is a romance in itself, but 

 is an example of the efficiency of the methods of archeology as well. 

 Here, briefly, is the story. 



Earlier in this paper it was stated that the Hohokam are believed to 

 have come into south-central Arizona around the beginning of the 

 Christian Era. At this point it may be stated that they disappeared 

 from the region around A. D. 1400, some three centuries prior to the 

 arrival upon the scene of Spanish explorers and adventurers from old 

 Mexico. For the evidence on which this chronology is based, we must 

 turn momentarily to another region and another people — the Pueblo 

 nations of the high plateau and canyons. 



Here in a region of evergreen forests, the ancient ruins of the 

 Pueblo peoples actually have been dated by means of tree-ring counts, 

 a technique developed by Dr. A. E. Douglass of the University of 

 Arizona. Details of this immeasurably important development can- 

 not be given in the limited space of this paper. It is one of the ro- 

 mances of American science. (See bibliography.) Suffice it to say 

 that most of the major ruins and scores of minor ones in the Southwest 

 now have been dated by this method, and that the chronology of the 

 region has been carried back to the first century A. D. 



As a result of the tree-ring method of dating, those ruins in forested 

 areas adjacent to the Hohokam country show significant changes 

 through the centuries in types and decorations of potteryware and in 

 virtually every aspect of their material culture; and since there was 

 more or less of trade and barter as between the two areas, the finding in 

 a Hohokam site of a Pueblo pottery vessel of, let us say, the period of 

 A. D. 1000, is suggestive to say the least. Multiply such individual 

 instances by any reasonable number, and at least a near-contemporane- 

 ity is the result. Although the Hohokam country is virtually lacking 

 in large trees, through such analogy and comparison its ruins are 

 dated. 



Finally, when all evidence of Hohokam activity ceases, and no fur- 

 ther objects known to pertain to other cultures appear in their ruins, 

 it is logical to assume that their career as a people was ended. Such 

 conditions are found to obtain not much later than A. D. 1400. 



The disappearance of so advanced a people from a region which 

 they had converted into an admirable place of residence was due to 

 two major causes. One of these is disclosed in a brief consideration 

 of the present-day situation. 



In the 1870's Mormon settlers appeared in the Salt River Valley 

 and began clearing out ancient irrigation canals and constructing 

 others. In the ensuing years this initial enterprise has grown by 



