The occupation of the site began around 900 BC, but until the Epi-Olmec period (400 BC-300 AD) it became the most important center in the region. At that time the Olmecs were already using the “zero” in their mathematicaoperations that were based on the use of bars and dots.
Within the site, the most prominent group is known as "the stream group" and it is located in the southwestern part of the site. The main mound of this group is known by local people as the "Camila hill " (where there stele D was found), which has 12 meters height above the plain. On the north side of the square there is the "long hill" (where the stele A was found), which is 7 meters high and 130 meters long, and the west end are two mounds of 5 meters high, which delimit a square of about 300 meters long by 200 meters wide.
Stratigraphic studies indicate that Tres Zapotes was affected by one or more of the San Martin volcano eruptions; probably that is why its inhabitants moved to higher lands.