This period (300 - 750 A.D.) falls mostly within the Classic Period. In the overall Mesoamerican developmental chronology. This is sometimes called the late urban period. In the Valley of Oaxaca regional chronology this corresponds to the Monte Albán III phase.
The Monte Albán III phase is usually divided into two sub-phases:
The Monte Albán IIIA phase is marked by by renewed growth and decentralization in the distribution of population, significant readjustments vertical social complexity and increased social integration.
The urban center at Monte Albán continued to serve as the capital of a state integrating the entire Valley of Oaxaca . However, it’s influence outside the Valley, with the exception of the Ejutla Valley to the south, appears to have declined, replaced in some locations by the influence of Teotihuacán in the Valley of Mexico.
There is also evidence of direct interaction between Teotihuacán. and Monte Albán during IIIA. Though it does not appear to have been “conquered” , the Valley of Oaxaca participates in some way in pan- Mesoamerican integration centered at Teotihuacán.
The Monte Alba´n IIIB phase is characterized by a sharp decline and recentralization in population at Monte Albán.
Unless otherwise indicated, this discussion is based on material drawn from: Blanton et. al ‘82 , Kowalewski, et. al. ‘89, Blanton, et. al. ‘93.