A number of important and well-known archaeological sites are found in the Oaxaca Valley, including Monte Albán, Mitla, San José Mogote and Yagul.

One of the earliest settlements in the Oaxaca Valley was San José Mogote, located in the northwestern part of the Etla arm.

Substantial cultural changes become evident during the Late Formative, including a dramatic population shift and the political centralization of the valley under the previously uninhabited capital of Monte Albán.

This inordinate population growth occurred simultaneously with the rapid abandonment of the other major centers occupying the three arms of the Oaxaca Valley (San José Mogote, Tilcajete, and Yegüih).

The rapid shift in population and settlement, from dispersed localized centers to a concentration in a previously unsettled area, has been referred to as the “Monte Albán Synoikism” by Marcus and Flannery.

[2] Throughout the remainder of the Late Formative, Monte Albán became the central point of political power and administrative activities in the Oaxaca Valley, forming a state-level society.

Monuments and murals at Monte Albán depict the arrival of visitors from Teotihuacan,[3] while there is evidence that a Zapotec “barrio” existed at the central Mexican city.

[6] In 1486, a fort would be established on the hill of Huaxyácac (now called El Fortín), overlooking the present city of Oaxaca and would become the seat of an Aztec garrison that enforced tribute collection from the Mixtecs and Zapotecs.

Several months later, on November 25, 1521, Francisco de Oruzco arrived in the Oaxaca Valley to claim it in the name of the conquistador Hernán Cortés.

In 1521, the Spanish settled in a community known as Segura de la Frontera, located in the central part of the Oaxaca Valley and approximately 9 km (5.6 mi) east of Monte Albán.