The Ojochi phase marks an early settled occupation at San Lorenzo and the start of long-term development that precedes the civic-ceremonial florescence of the Olmec center.
Offerings deposited in the El Manatí sacred bog (near San Lorenzo) date to c. 1600 BCE or earlier, indicating early ceremonial traditions in the region before San Lorenzo’s civic center reached prominence.
During the Bajío phase, inhabitants expanded occupation and began significant filling/leveling and terracing on the San Lorenzo landform—foundational civic works that enabled later monumental construction on the plateau.
In the Chicharras phase, more characteristically Olmec-style artifacts appear at San Lorenzo, signaling a clearer cultural shift toward what is widely recognized as early Olmec material culture.
The San Lorenzo phase corresponds to the site’s major florescence, when San Lorenzo became a leading Gulf Coast center and the civic-ceremonial core was extensively developed.
San Lorenzo’s core was built on extensive high ground and further modified through large-scale filling and leveling, creating a designed civic landscape that supported elite residences and monument settings.
San Lorenzo’s rulers commissioned major basalt monuments (including thrones and later colossal heads), with stone brought from the Tuxtla Mountains region—evidence of organized labor and long-distance transport.
San Lorenzo’s ten colossal heads were arranged in the civic center (likely as part of a processional/monumental route with thrones). Their later burial by about 900 BCE implies they were carved and used earlier than that date.
San Lorenzo developed an engineered drainage system using buried, covered, channeled stones (often described as “pipes”), directing water across and off the plateau—an important civic technology with possible ritual dimensions.
At the start of the Middle Formative (the Nacaste phase), San Lorenzo began to decline, marking a transition away from its earlier dominance and suggesting shifting political and demographic conditions in the Olmec heartland.
Around 900 BCE, San Lorenzo’s civic center was destroyed (Britannica notes possible invasion) and many stone monuments were deliberately damaged/mutilated and buried, signaling a decisive political rupture at the site.
In 1945, archaeologist Matthew W. Stirling discovered/excavated San Lorenzo Colossal Head 1 (Monument 1), a milestone that helped establish San Lorenzo’s importance in Olmec studies.
The 1946 expedition work near San Lorenzo (National Geographic Society/Smithsonian) reported the discovery of multiple huge heads at the site, drawing broad attention to San Lorenzo’s monumental sculpture tradition.
San Lorenzo Tenochtitlán civic center (c. 1400–900 BCE)
