for agricultural production in the pre Hispanic and colonial eras. The climate is temperate and semi moist with rains in the summer. Average temperatures range between 18 and 20C. January is the coldest months with average temperatures of between 10 and 16C, and May is the warmest with averages between 20 and 22C. The only forested area is an area associated with the Sierra del Tentzo, which contains holm oak and scrub. The rest of the area is either farmland or covered by human settlements. History The first human settlements of Cholula are within the confines of the San Andrés municipality and date somewhere between 500 and 200 BCE, during the middle Preclassic period. Through the Classic period, the village grew and social hierarchy developed, with the first pyramid to define this social and religious hierarchy begun at the end of the Preclassic. At the end of this period, many settlements were abandoned, but Cholula grew, making it politically dominant in the region. It rapidly developed into an urban center in the Classic period (200–800 CE) dominating the Puebla-Tlaxcala region, growing to an area of about four km2 and a population of between 20,000 and 25,000. The Great Pyramid was expanded twice during this time. The city had relations with the larger Teotihuacan, but the nature of this is not known. However, at the end of the Classic period, Teotihuacan fell. Cholula had a population decline but the city survived. However, there is evidence of a change of dominant ethnicity, with a people known as the Olmec-Xicallana coming to power and pottery and other artifacts showing Gulf Coast influence. The city continued to grow during the Post Classic period (900–1521) as well, although there was another regime change. Toltec-Chichimecas from the fall the Tula arrived in the 12th century as refugees. The ruling Olmeca-Xicallanca allowed their arrival but oppressed them, until the Toltec-Chichimecas revolted and took over in the 13th century. The new lords called themselves the Choloteca, but they did not eliminate the Olmeca-Xicallanca. The defeated group was pushed to the eastern half of the city and the surrounding areas, maintaining a certain amount of religious and political autonomy, centered on the pyramid. This is the origin of the San Andrés municipality. At around this same time, there was significant destruction on the Great Pyramid, especially the latest constructions. By the time the Spanish arrived, Cholula was actually divided