Today, the impressive ruins of Monte Alban, Mitla, and Yagul (among others) stand as testimony to the accomplishments of the pre-Hispanic Zapotee. Prior to the arrival of the Spanish, the Zapotee developed a powerful state system that flourished and then declined. Long before the rise of the state (ca. 8000 to 1,500 B . C .), the Zapotee and the related Mixtec camped in small groups probably of twenty-five persons or less. Permanent villages appeared during the Formative period (ca. 1,500 to 100 B . C .) as did various new customs and practices, including loom weaving, adobe construction, stone masonry, pottery making, a 260-day calendar, human and animal sacrifice, and redistribution and reciprocal exchange systems. During the Classic period (ca. A . D . 300 to 900), Monte Alban was the metropolis of the Zapotee area, the center of a state organization that exerted its influence throughout southern Mexico. The Postclassic (ca. A . D . 900 to 1520) was the time of competitive Zapotee city-states. During the fifteenth century, the Aztec occupied the central valley and founded a garrison that would later become the state capital, Oaxaca City. When the Spanish arrived in Oaxaca, this garrison served as their colonial headquarters. Compared with the Aztec invasion, the Spanish presence in Oaxaca was exploitative and religious rather than military; compared to many parts of Mexico, most Zapotee communities remained relatively autonomous. Presently, through the market system, the Zapotee have contact with other indigenous groups and mestizos.