[1] Cultures of the Classic Stage are supposed to possess craft specialization and the beginnings of metallurgy.
Social organization is supposed to involve the beginnings of urbanism and large ceremonial centers.
[2] The "Classic Stage" was initially defined as restricted to the complex societies of Mesoamerica and Peru.
However, the time period includes other advanced cultures, such as Hopewell, Teotihuacan, and the early Maya.
[3] There are alternative classification systems, and this ranking would overlap what others classify as the Woodland period and Mississippian cultures.