state is a quartz scraper and obsidian blade found in the Tlapacoya area, which was an island in the former Lake Chalco. They are dated to the Pleistocene era which dates human habitation back to 20,000 years. These first peoples were hunter-gatherers. Stone age implements have been found all over the territory from mammoth bones, to stone tools to human remains. Most have been found in the areas of Los Reyes Acozac, Tizayuca, Tepexpan, San Francisco Mazapa, El Risco and Tequixquiac. Between 20,000 and 5,000 B.C.E., the people here eventually went from hunting and gathering to sedimentary villages with farming and domesticated animals. The main crop was corn, and stone tools for the grinding of this grain become common. Later crops include beans, chili peppers and squash grown near established villages. Evidence of ceramics appears around 2,500 B.C.E. with the earliest artifacts of these appearing in Tlapacoya, Atoto, Malinalco, Acatzingo and Tlatilco. History Toward the fifth Millennium BCE, Oto-Manguean languages speaking peoples formed a large unit. Language diversification and geographical expansion, which has been proposed as their "Urheimat", that is, the Tehuacán valley (current state of Puebla) should have occurred after the domestication of the Mesoamerican agricultural Trinity, composed by Corn, Beans and Chile pepper. This is based on the large amount of cognates in the repertoire of words alluding to agriculture in the Oto-manguean languages. After the development of an incipient agriculture, the proto-manguean language gave rise to two distinct languages that constitute the current eastern and western groups of the Oto-manguean family background. Continuing with the linguistic evidence, it seems likely that Pames - members of the western branch - reached the Basin of Mexico around of the fourth millennium of the Christian era and that, in what some authors argue, have not migrated northward but south. The earliest major civilization of the state is Teotihuacan, with the Pyramids of the Sun and Moon being built between 100 B.C.E and 100 C.E. Between 800 and 900 C.E., the Matlatzincas established their dominion with Teotenango as capital. This city is walled with plazas, terraces, temples, altars, living quarters and a Mesoamerican ball game court. In the 15th century, the Aztecs conquered the Toluca and Chalco valleys to the west and east of the Valley of Mexico respectively. Part of the Toluca Valley was held by the Purépecha as well. Other dominions during the pre-Hispanic period include that of the