In Portuguese, the word sertão (Portuguese pronunciation: [sexˈtɐ̃w̃], "backcountry" or "outback") first referred to the vast hinterlands of Asia and South America that Lusitanian explorers encountered. In Brazil, the geographical term referred to backlands away from the Atlantic coastal regions where the Portuguese first settled in South America in the early sixteenth century. A Brazilian historian once referred to colonial life in Brazil as a "civilization of crabs", as most settlers clung to the shoreline, with few trying to make inroads into the sertão. In modern terms, "sertão" usually refers to the semi-arid region in Northeastern Brazil comprising parts of the states of Alagoas, Bahia, Pernambuco, Paraíba, Rio Grande do Norte, Ceará and Piauí. The plural of sertão is sertões. The term "sertanejo" is similar to the generic use of "cowboy" in the United States.
Geographically, the sertão consists mainly of low uplands that form part of the Brazilian Highlands. Most parts of the sertão are between 200 and 500 meters above sea level, with higher elevations found on the eastern edge in the Planalto da Borborema, where it merges into a sub-humid region known as agreste, in the Serra da Ibiapaba in western Ceará and in the Serro do Periquito of central Pernambuco. In the north, the sertão extends to the northern coastal plains of Rio Grande do Norte state, whilst in the south it fades out in the northern fringe of Minas Gerais.
Two major rivers cross the sertão, the Rio Jaguaribe and the Rio Piranhas further east. Apart from the Rio São Francisco which originates outside the region, other rivers dry out after the rainy periods end.
Climate and vegetation 
|Climate chart (explanation)|
Because the sertão lies close to the equator, temperatures remain nearly uniform throughout the year and are typically tropical, often extremely hot in the west.
However, the sertão is distinctive in its low rainfall compared to other areas of Brazil. Because of the relatively cool temperatures in the South Atlantic Ocean, the intertropical convergence zone remains north of the region for most of the year, so that most of the year is very dry.
Although annual rainfall averages between 500 and 800 millimeters over most of the sertão and 1300 millimeters on the northern coast at Fortaleza, it is confined to a short rainy season. This season extends from January to April in the west, but in the eastern sertão it generally occurs from March to June. However, rainfall is extremely erratic and in some years the rains are minimal, leading to catastrophic drought, whilst in others rains are extremely heavy and floods occur. This variability has caused extreme famines among subsistence farmers in the region, exacerbated by the extreme imbalance of land ownership throughout the sertão. The worst of these famines, between 1877 and 1879, was said to have killed over half the region's population.
In its natural state, the sertão was covered by a distinctive scrubby caatinga vegetation, consisting generally of low thorny bushes adapted to the extreme climate. Several species of tree in the caatinga have become valuable horticultural plants, such as the cashew nut. Most of the sertão vegetation is now substantially degraded as a result of centuries of cattle ranching or clearing for cotton farming.
Parts of the sertão are recognized as a biodiversity hot-spot because of the unique flora.
See also 
- Wernstadt, Frederick L. ; World Climatic Data; published 1972 by Climatic Data Press; p. 102.
- Michael H. Glantz; Currents of Change : El Niño's Impact on Climate and Society; published 1996 by Cambridge University Press. ISBN 0-521-57659-8
- Michael H. Glantz (editor); Drought Follows The Plow: Cultivating Marginal Areas; published 1994 by Cambridge University Press. ISBN 0-521-44252-4
- Fagan, Brian; Floods, Famines, and Emperors: El Niño and the Fate of Civilizations; published 2000 by Basic Books. ISBN 0-465-01121-7
- Nicholas G. Arons; Waiting for Rain: The Politics and Poetry of Drought in Northeast Brazil; published 2004 by University of Arizona Press. ISBN 0-8165-2433-5
- Euclides da Cunha, Rebellion in the Backlands