Archaeologists have identified three sites in the reserve with artifacts dating back 8,000 years. The plateau has been a transit corridor for most of human history in central Brazil - indigenous peoples crossed it for millennia, and by the colonial era it was part of the Royal Road of Bahia, a cattle-and-cargo route connecting the mines of the Minas Gerais highlands to Bahia's Atlantic ports. The first written record of European passage dates to 1734, when a drover moved livestock across the region. Two years later, in 1736, the Portuguese crown established the Contagem de Sao Joao das Tres Barras - a customs post where royal agents took their cut of the gold and goods flowing between Tocantins, Goiás, and Minas Gerais. The post also counted the enslaved Africans being forced along the route to work the mines. Blood and taxes moved across this land for three centuries before anyone proposed to protect what else lived here.

The reserve was formally created on December 13, 2002, and classified by the IUCN as Category Ia - a strict nature reserve, the most protective designation, intended to preserve biota without direct human interference. Its purpose is straightforward. To the south sits Brasília National Park, an island of protected cerrado inside the Federal District. To the north, the Maranhão River basin flows toward the Tocantins and the Amazon. Without a connecting corridor, animals in the national park would be isolated from the broader cerrado system. Contagem provides that link. The reserve contains the escarpment and the top of the Chapada da Contagem - the Contagem plateau - at altitudes between 1,000 and 1,200 meters. The escarpment is steep, the top flat. Two river systems rise within it: the Contagem River and the Paranoazinho stream, which supply drinking water to the Sobradinho satellite city to the south.

Giant anteaters, Myrmecophaga tridactyla, move through the reserve - long-snouted, slow, ant-and-termite specialists that need large ranges to find enough mounds to feed a 30-kilogram body. Giant armadillos, Priodontes maximus, use the same corridors. The yellow-faced parrot, Alipiopsitta xanthops, disperses between Brasília National Park and the Maranhão basin using the reserve as a flyway. Vanderhaege's toad-headed turtle, Mesoclemmys vanderhaegei, inhabits the streams. A rare frog, Bokermannohyla pseudopseudis, breeds in the rocky streambeds. The vegetation ranges from cerrado sensu stricto (the classic scattered tree savanna) to denser cerradão and open campo sujo grassland. Annual rainfall averages 1,454 millimeters, nearly all of it falling between October and March. Temperatures average 20 degrees Celsius, comfortable by cerrado standards, with occasional frosts on cold-front mornings in June and July.

The protection is unequal. Only 54 percent of the reserve is clearly public land - the rest is private property, contested title, or unregularized claims, a legacy of the speculative land grabs that accompanied Brasília's creation. Before the reserve's legal protection existed, settlements had already penetrated the area. The Basevi village, in the center of the reserve, grew up around an old gravel quarry that supplied stone for Brasília's construction in the late 1950s. Today Basevi holds more than 4,000 people, two asphalt plants, schools, and no sewage system. The prosperous Grande Colorado walled community stretches into the reserve from the east. Illegal trails thread the protected land from several neighborhoods. People enter for fishing, barbecues, leisure - some race motor bikes on the dirt trails, poach animals, dump oil and shampoo bottles in the streams. Transients live and cook fires in the reserve. Sewage and garbage get dumped illegally. Livestock sometimes intrude.

The reserve is administered by the Chico Mendes Institute for Biodiversity Conservation, the federal agency responsible for Brazil's protected areas. As of 2009 - the last published staffing figure - only three personnel were assigned to Contagem, and they were based at the national park to the south rather than at the reserve itself. No headquarters. No monitoring stations. No rangers patrolling the boundaries. The management document on paper guarantees strict protection. The reality on the ground is a reserve that exists primarily because of what the neighbors have not yet built. And yet the corridor holds. Anteaters still move through. The yellow-faced parrots still disperse between Brasília National Park and the Maranhão basin. The cerrado vegetation still regenerates after the dry-season burns. The reserve is one of the most fragile pieces in Brazil's protected-area system, and also one of the most important - a three-thousand-hectare hinge connecting the capital's last wild spaces to the larger ecosystem of which they were once part.