The Olmec civilization, often considered the "mother culture" of Mesoamerica, thrived from around 1200 to 400 BCE in present-day Mexico. They are known for their impressive colossal heads, which are large stone sculptures representing their rulers. The Olmec society was organized into city-states, with San Lorenzo and La Venta being two of the most significant centers. Olmec society was characterized by a complex social structure, including a ruling elite, artisans, and farmers. They engaged in trade, exchanging goods like jade and obsidian, and developed early forms of writing and a calendar system. Their religious beliefs included a pantheon of gods, often depicted in their art and architecture.