Source: Billman, Brian. (1996) The Evolution of Prehistoric Political Organizations in the Moche Valley, Peru. Unpublished Ph.D. Dissertation. Department of Anthropology, University of California, Santa Barbara.
Bill, Brian R. (1999) Reconstructing Prehistoric Political Economies and Cycles of Political Power in the Moche Valley, Peru. In Settlement Pattern Studies in the Americas: Fifty Years Since Virú, edited by B. R. Billman and G. M. Feinman, pp.131-159. Smithsonian Institution Press: Washington D.C.
Brian Billman synthesized survey data from Chan Chan-Moche Valley Project (1969-75), directed by Michael Moseley and Carol Mackey, with his own fieldwork in the middle Moche Valley (1990-91). Sites were located using aerial photographs and maps purchased from Oficina General de Catastro Rural. Billman utilized a non-random, selective strategy in choosing areas of intensive survey based on judgment of site density. Data regarding longitude, latitude, or UTM information were not included in Billman's publications.
The survey documented a movement of sites toward the mid-valley. During the Late Preceramic Period, all of the recorded sites (2) were located near the coast. In the subsequent Early Formative Period, all sites identified in the survey were found in the mid-valley.