The Postclassic Period is a time between the year 900 and 1521, the conquest of Mesoamerica by the Spaniards. It followed the Classical Period of Mesoamerica. The several cultures possessed advanced metallurgy and social organization. It was characterized by complex urbanization and military activity became every important during that time. Ideologically, postclassical cultures are described as tending towards a secularization of society. Cultures included in that period are the Incas, Aztec, Tarascan, Mixtec, Totonacs, Pipil, Itza, Kowoj, K’iche’, Kaqchikel, Poqomam and Mam.

It is divided in two phases. The Early Postclassic Period until the 13th century and the Late Postclassic Period after that. Toltec characterized the first period, where the second saw the arrival of the Chichimec. Many of the social changes of the final period are related to the migration of the northern peoples. They were driven by climate changes that threatened their survival.

There were many cultural changes. The expansion of metallurgy from South America was one of them. Mesoamericans didn’t achieve great facility with metals. Their use was limited. The most advanced techniques of their metallurgy were developed for fine, exquisitely handcrafted articles. The use of nails in their architecture was another remarkable advancement. It helped supporting the sidings of the temples, mortar was improved, and they began to use columns and stone roofs. Only the Maya used that during the Classic Period. The system of irrigation became more complex in the Valley of Mexico.

During the early Postclassic Period, the warlike political elites legitimized their position by means of a complex set of religious beliefs. According to this system, the rulers proclaimed the descendants of Quetzalcoatl, the Plumed Serpent, a cultural hero in Mesoamerican mythology. They declared themselves the heirs of the mystical city, Tolan. Many important capitals of the time identified themselves with this name. Alliances were formed with other city-states, controlled by groups with the same ideology.

With the fall of Tula (Tolan), the power broke down. Mesoamerica received new immigrants from the north with different ideology, although they were related to the ancient Toltecs. The Mexica were the final arrivals.

They established themselves on a small island on Lake Texcoco. This group would conquer larger parts of Mesoamerica. They created a united and centralized state wit ha non-aggression pact with the Tarascan state of Michoacán, their rivals they could not defeat. Many peoples controlled by the Mexica no longer wished to be ruled. When the Spaniards arrived, these people agreed to support the Europeans. The believed they would regain their freedom, not knowing this would lead to the subjugation of all the Mesoamerican world.