Drought in Sertao, at Barra de Santa Rosa city, Paraiba State, Northeast Brazil. People dig a dry river bed in search for some brackish water. Sertao usually refers to the semi-arid region in Northeastern Brazil comprising parts of 7 states. Although annual rainfall averages between 500 and 800 millimeters over most of the sertão, it is confined to a short rainy season. 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 sertao. The worst of these famines, between 1877 and 1879, was said to have killed over half the region's population.