Guachimontones are possibly an outgrowth of earlier Middle Formative burial mounds, such as the one documented near San Felipe by Weigand. These large, low mounds once contained dozens of burials before looters and construction activities destroyed these mounds. While burials typically are not found within the altars of a guachimonton, there may be some continuity in cosmological belief from the Middle Formative to Late Formative periods. Based on a limited number of excavations of guachimontones, the earliest dated guachimonton is that of Circle 1 and Circle 6 at Los Guachimontones. These two structures, despite their drastic difference in size, date to the Tequila II phase (300 to 100 BCE). Circle 6 is notable for containing several secondary burials within its altar, possibly part of a place-making ritual involving important ancestors.