Around 500 BC, a major settlement was founded at Monte Alban in the very heart of the Oaxaca valley. Its highly defensible hilltop position might have been an important factor in the choice of this site; but its central location would seem primarily to indicate a centralization and merging of the interests of the valley's separate chiefdoms.
Thereafter the Zapotec people of the valley seem to have turned their attentions outwards, conquering neighbouring regions, victories over which were recorded on stelae (carved monoliths) at Monte Alban.
Expansion was halted around AD 300 when Monte Alban ran into competition from the growing Teotihuacan Empire; but relations with this state seem to have been peaceful.
Although the city of Monte Alban housed 25,000 or 30,000 people, most of the valley's craft and commercial activities continued in the villages, Monte Alban being the religious and political capital. Here dwelt the rulers and the elite, who were buried in great underground tombs complete with luxury grave goods including the famous Zapotec urns.
