The Amazon was probably first seen by Europeans in 1500 when the Spanish commander Vicente Yáñez Pinzón explored the lower part. Real exploration of the river came with the voyage of the Spanish explorer Francisco de Orellana down from the Napo in 1540–41; his stories of female warriors gave the river its name. Not long afterward (1559) the Spanish conquistador Pedro de Ursúa led an expedition down from the Marañón River. In 1637–38 the Portuguese explorer Pedro Teixeira led the voyage upstream that definitively opened the Amazon to world knowledge. The river continued to be of enormous importance to explorers and naturalists, among them Charles Darwin and Louis Agassiz.
There is archaeological evidence of clustered, densely populated pre-Colombian settlements in parts of the Amazon basin, but at the time of the early European explorations these settlements had already been wiped out, probably by smallpox and other diseases, The valley was largely left to its sparse remaining indigenous inhabitants (mostly groups of the Guaraní-Tupi linguistic stock and of meager material culture) until the mid-19th cent., when steamship service was regularly established on the river and when some settlements were made. In the late 19th and early 20th cent., the brief wild-rubber boom on the upper Amazon attracted settlers from Brazil's northeastern states, and in the 1930s Japanese immigrants began developing jute and pepper plantations. Until recently the area remained largely unpopulated, yielding small quantities of forest products (rubber, timber, vegetable oils, Brazil nuts, and medicinal plants) and cacao.
The establishment of a health service (chiefly by launch) in World War II was followed by the creation of a UNESCO research institute in 1948, and several developmental programs, both governmental and private, were set up in Brazil to foster the valley's development. In the 1960s the Amazon region began experiencing increased economic development brought on by tax incentives and construction of the Trans-Amazon Highway, the Belém-Brasília Highway, and two rail lines. Near Manaus and Amapá, factories make use of ample oil and manganese resources. In addition, a port at the Brazilian city of Macapá was connected by rail in the 1950s to the inland stores of manganese.
The Brazilian government implemented a "poles of development" policy in 1974 to plan for population increase. Since 1985 areas in the Amazon region have seen the exploitation of mineral deposits, land colonization, cattle ranching, large-scale farming, and urban development on an unprecedented scale. This has had mixed results, leading to environmental damage, including significant deforestation, and to the disruption of the original inhabitants' lives, and many settlers in the region do not have title to their land. In 2009 a law was passed that would permit settlers to acquire title, either through a grant or purchase, depending on the size of the plot. The destruction of large sections of the rain forest has threatened rare species of plants and contributed to the increase in the atmosphere's carbon dioxide and the consequent impact on global warming.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.