Conversation so far:
What is an indigenous group?
The indigenous peoples of the Americas are the pre-Columbian peoples of North, Central and South America and their descendants.
Who are The Olmecs?
The territory of modern-day Mexico was home to numerous indigenous civilizations prior to the arrival of the Spanish conquistadores: The Olmecs.
What other cultural elements did The Olmecs have?
The aspect of the Olmecs most familiar now is their artwork, particularly the aptly named colossal heads. The Olmec civilization was first defined through artifacts.
Did The Olmec's culture change?
Scholars haven't determined the cause of the eventual extinction of the Olmec culture. Between 400 and 350 BCE, the population in the eastern half of the Olmec heartland dropped precipitously

Question: What happened in the aftermath?
Self-contained rewrite: What happened in the aftermath of the precipitous population drop in the eastern half of the Olmec heartland?