In the subsequent formative eras, maize cultivation and cultural traits such as a mythological and religious complex, and a vigesimal (base 20) numeric system, were diffused from the Mexican cultures to the rest of the Mesoamerican culture area. In this period, villages became more dense in terms of population, becoming socially stratified with an artisan class, and developing into chiefdoms. The most powerful rulers had religious and political power, organizing the construction of large ceremonial centers.