Chronology 5000 BCE Some of the first plants begin to be cultivated in the Americas. Ethnobotanical studies locate the first plant domestication in the Tehuacán-Cuicatlán Valley of central Mexico. 3000 BCE Complex societies, with monumental architecture and major residential centers, develop at sites in the Norte Chico region of Peru. 2600 BCE The Maya civilization begins early city-state settlements. The first known Maya city, Cuello, located in Belize, has been dated to 2600 BCE. 1200 BCE The Olmecs, one of the earliest complex societies, establish the first city in the Americas, San Lorenzo. 150 BCE Some of the earliest instances of writing in Mesoamerica are from this era and can be found in the Zapotec area of the Valley of Oaxaca. 50 BCE The Mayan place-value system is developed to represent numbers. Their knowl- edge of astronomy and mathematics lead them to create different calendars, including the Long Count calendar and the Calendar Round, a cycle of fifty-two years. 500 Many city-states flourish during the Classic period in Mesoamerica. The ancient Maya city of Tikal is one such city-state. 950 Toltecs arrive from the north and settle in the Valley of Mexico, establishing their capital city in Tula (now Hidalgo). 1150 A nomadic tribe from the northern territories, the Aztecs, begin to move south from their original homeland, which they call Aztlan (or “White Land” in Nahuatl).