The Oaxaca Valley, the cradle of Zapotec civilization, is a broad valley in the north-eastern part of state of Oaxaca located about south of Mexico City. Mountains surround the valley with The Sierra Madre Oriental in the north and the mountains of Tlacolula in the southeast. The area's environment is well suited for agriculture, especially the cultivation of maize, making it a desirable place for settlers. The valley floor is mostly flat with large tracts of arable land. At the time of the emergence of Zapotec civilization, the valley soil had not suffered erosion, since the oak-pine forest surrounding the valley was intact. The climate the temperate climate is ideal for maize cultivation, and it possible to harvest crops several times a year. Frost rarely occurs as it does at higher altitudes in the region. The high agricultural potential in The Valley of Oaxaca has certainly contributed to making this area become the locus of the first complex societies in the Valley of Oaxaca.