Indian dark earth

There is ample evidence that the areas surrounding the Amazon River were home to complex and large-scale indigenous societies, mainly chiefdoms who developed towns and cities.[citation needed] Archaeologists estimate that by the time the Spanish conquistador De Orellana traveled across the Amazon in 1541, more than 3 million indigenous people lived around the Amazon.[22] These pre-Columbian settlements created highly developed civilizations. For instance, pre-Columbian indigenous people

on the island of Marajó may have developed social stratification and supported a population of 100,000 people. To achieve this level of development, the indigenous inhabitants of the Amazon rainforest altered the forest’s ecology by selective cultivation and the use of fire. Scientists argue that by burning areas of the forest repeatedly, the indigenous people caused the

soil to become richer in nutrients. This created dark soil areas known as terra preta de índio (“Indian dark earth”).[23] Because of the terra preta, indigenous communities were able to make land fertile and thus sustainable for the large-scale agriculture needed to support their large populations and complex social structures. Further research has hypothesized that this practice began around 11,000 years ago. Some say that its effects on forest ecology and regional climate explain the otherwise inexplicable band of lower rainfall through the Amazon basin.[23]

Many indigenous tribes engaged in constant warfare. According to James S. Olson, “The Munduruku expansion (in the 18th century) dislocated and displaced the Kawahíb, breaking the tribe down into much smaller groups … [Munduruku] first came to the attention of Europeans in 1770 when they began a series of widespread attacks on Brazilian settlements along the Amazon River.”[24]