Because of scant rainfall on the coast, the main source of water is the rivers which rise in the Andes to the east and flow westward to the Pacific ocean. These rivers slice the desert, creating oasis-like valleys. These valleys are natural and formed over thousands of years. Ancient Peruvians gave them shape, using irrigation and other native technologies to turn them into rich and productive farmland.

One of these north coast valleys, the Moche or Santa Catalina, served from the first to the eighth centuries after Christ as the seat of the capital of one of Peru’s most thriving coastal societies: the Moche.