The first humans arrived in the Amazon rainforest roughly 13,000 years ago, during the late Pleistocene era when massive ice sheets still covered parts of North America. These early foragers moved quickly through the region, leaving traces across a vast area. Far from being a pristine, untouched wilderness, the Amazon has been shaped by human hands for millennia, with its inhabitants building cities, domesticating crops, and engineering fertile soils long before Europeans ever set foot in South America.
The Earliest Evidence: 13,000 Years Ago
The best direct evidence of the Amazon’s first inhabitants comes from Caverna da Pedra Pintada, a cave near Monte Alegre in the Brazilian Amazon. Fifty-six radiocarbon dates on carbonized plant remains and thirteen luminescence dates on stone tools and sediment place human occupation there in the late Pleistocene, making these Amazonian foragers contemporaries of the Paleoindian cultures of North America. Inside the cave, archaeologists found triangular spear points, paintings, and other tools that document a culture clearly distinct from anything found farther north.
These weren’t struggling survivors clinging to the edges of the forest. Carbonized tree fruits, wood, and animal remains found at the site reveal a broad-spectrum diet built around tropical forest and river resources. The early Amazonians were already well adapted to the humid, densely forested environment, hunting, fishing, and gathering a wide variety of plant foods.
How They Got There
Genomic studies have pieced together the likely migration paths into South America. The first groups carrying what scientists call the Southern Native American lineage crossed through Central America and entered the continent, spreading initially along the Pacific coast and settling the Andes. At least one major population split occurred soon after, probably somewhere around the Andean region. One branch headed toward the Atlantic coast, while others pushed into the continental interior.
A 2024 genomic study estimated that early migrants in South America split into four broad groups, Amazonians, Andeans, Chaco Amerindians, and Patagonians, approximately 13,900 years ago. Over the thousands of years that followed, geographic barriers like mountain ranges, rivers, and dense forest further isolated these groups from one another, reducing genetic diversity within each population. Present-day Indigenous groups like the Surui and Karitiana of the Amazonian rainforest carry genetic ancestry tracing back to one of the ancient clades identified in Pacific coastal archaeological sites.
From Foragers to Farmers
The transition from nomadic foraging to settled life happened gradually over thousands of years. The earliest sedentary sites in the Amazon date to between 9,000 and 8,000 years ago. Around 4,000 years after the first foragers arrived, the first villages appeared, leaving behind substantial shell middens (mounds of discarded shells, bones, and food waste) and visible disturbances in the surrounding forest.
After roughly another 4,000 years, many communities turned to shifting horticulture: cutting and burning small clearings, planting crops, and moving on when the soil’s fertility declined. The Amazon was one of the world’s major centers of plant domestication. Selection of wild plants began as early as the late Pleistocene to early Holocene. Cacao, originally native to the Amazon, was being used across South America by at least 5,000 years ago, with traces found in southern Ecuador. Manioc and maize were adopted in Colombian tropical forests by the middle Holocene, roughly 5,000 to 7,000 years ago. Cupuaçu, a popular Amazonian fruit tree, may have been under domestication for 8,000 years.
Cities Hidden Beneath the Canopy
The popular image of the pre-contact Amazon as a scattering of small tribal groups living lightly on the land is increasingly outdated. In the last 3,000 years of prehistory, networks of populous, warring chiefdoms established large centers along floodplains and trade routes. They built mound complexes, defensive earthworks, agricultural fields, and orchards that dramatically altered the landscape’s topography, soils, and vegetation.
The most striking recent discovery came from Ecuador’s Upano Valley, where laser mapping (lidar) revealed a dense network of interconnected cities hidden beneath the forest canopy. Radiocarbon dating places these settlements from around 500 B.C.E. to somewhere between 300 and 600 C.E. The team identified five large settlements and ten smaller ones across 300 square kilometers, each packed with residential and ceremonial structures. The core area of one site, Kilamope, covers an area comparable in size to Egypt’s Giza Plateau or the main avenue of Teotihuacan in Mexico. At roughly 2,500 years old, these are more than a millennium older than other known complex Amazonian societies, including the recently discovered ancient urban system at Llanos de Mojos in Bolivia.
Engineering the Soil Itself
Perhaps the most lasting mark left by ancient Amazonians is terra preta, patches of dark, extraordinarily fertile soil scattered across central Amazonia. Natural Amazonian soils tend to be nutrient-poor and acidic, but terra preta is rich in organic carbon, nutrients, and charcoal. Radiocarbon dating indicates these soils were created between 7,000 and 500 years ago.
Pre-Columbian populations generated terra preta by adding large amounts of charred residues, organic waste, excrement, and bones to the soil over long periods. Some of this may have been intentional soil engineering; some likely resulted from everyday activities like cooking over low, smoldering fires. Either way, these soils remain remarkably fertile centuries later and are now studied as a model for sustainable agriculture. Their existence across wide areas of the Amazon is itself evidence of dense, long-term human settlement in places that were once assumed to have been too remote or inhospitable for large populations.
A 13,000-Year Relationship
The Amazon’s human story stretches back nearly as far as the presence of people anywhere in the Americas. Within a few thousand years of arrival, foragers had settled into permanent communities. Within several more, they were domesticating crops that would become staples across the continent. By 2,500 years ago, some groups were living in urban networks rivaling the complexity of Mesoamerican civilizations. The rainforest that exists today is not a wilderness untouched by human hands. It is, in many ways, a landscape that humans helped build over 130 centuries of continuous habitation.