During the Formative Period, human settlements began to move inland (Moseley 1992). This pattern was reflected by archaeological surveys, which showed that Formative sites were located further inland as compared to the earlier Preceramic sites. The shift in settlement distribution probably resulted from greater reliance on cultivated plants and irrigation systems that operated most optimally in mid- or upper valley.Click on the Moche, Viru, Santa, or Jequetepeque valley to show more detailed settlement data.