7 dated entries naming Olmec, drawn from 6 separate years between 1600 BCE and 400 BCE. Nothing here is written by us: each line is the sentence a Wikipedia year article used, and the link beside it opens the exact revision.
1600 BCEc. 1600 BC—The foundations of the Olmec civilization in southern Mexico.source
12th century BC
1200 BCEc. 1200 BC: Olmec culture starts and thrives in Mesoamerica.source
9th century BC
900 BCEc. 900 BC — San Lorenzo, the center of early Olmec culture, is destroyed, probably by migrating peoples from the north, and power passes to La Venta in Tabasco.source
900 BCEc. 900 BC – 600 BC — Great Pyramid and ball court, La Venta, Mexico, is built. Olmec culture.source
6th century BC
600 BCEThe calendrical system begins appearing in areas with strong Olmec influence, continuing to appear until 500 BC (approximate date).source
5th century BC
500 BCEThe Olmec established Monte Albán, the sacred city, and continued building pyramids. Founded toward the end of the Middle Formative period at around 500 BCE, by the Terminal Formative (ca.100 BCE–CE 200) Monte Albán soon became the capital of a large-scale expansionist polity that dominated much of the Oaxacan highlands and interacts with other Mesoamerican regional states, such as Teotihuacan to the north (Paddock 1983; Marcus 1983).source
4th century BC
400 BCEThe Olmec culture in Mesoamerica comes to an end as its city of La Venta is abandoned (approximate date).source