Editing Olmecs (section)

===Decline===
Scholars have yet to determine the cause of the eventual extinction of the Olmec culture. Between [[4th century BC|400 and 350&nbsp;BCE]], the population in the eastern half of the Olmec heartland dropped precipitously, and the area was sparsely inhabited until the 19th century.<ref>Diehl, p. 82. Nagy, p. 270, however, is more circumspect, stating that in the [[Grijalva river]] delta, on the eastern edge of the heartland, "the local population had significantly declined in apparent population density&nbsp;... A low-density Late Preclassic and Early Classic occupation ... may have existed; however, it remains invisible."</ref> According to archaeologists, this depopulation was probably the result of "very serious environmental changes that rendered the region unsuited for large groups of farmers", in particular changes to the riverine environment that the Olmec depended upon for agriculture, hunting and gathering, and transportation. These changes may have been triggered by [[tectonic]] upheavals or subsidence, or the [[siltation]] of rivers due to agricultural practices.<ref>Quote and analysis from Diehl, p. 82, echoed in other works such as Pool.</ref>

One theory for the considerable population drop during the Terminal Formative period is suggested by Santley and colleagues (Santley et al. 1997), who propose the relocation of settlements due to volcanism, instead of extinction. Volcanic eruptions during the Early, Late and Terminal Formative periods would have blanketed the lands and forced the Olmec to move their settlements.<ref>Vanderwarker (2006) pp. 50–51</ref>

Whatever the cause, within a few hundred years of the abandonment of the last Olmec cities, successor cultures became firmly established. The Tres Zapotes site, on the western edge of the Olmec heartland, continued to be occupied well past [[400 BCE]], but without the hallmarks of the Olmec culture. This post-Olmec culture, often labeled the [[Epi-Olmec culture|Epi-Olmec]], has features similar to those found at [[Izapa]], some {{convert|550|km}} to the southeast.<ref>Coe (2002), p. 88.</ref>