On All Saints' Day, November 1, 1501, Portuguese explorers entered the bay on which Salvador now stands: they therefore named it Baía de Todos os Santos (Todos os Santos Bay), or All Saints' Bay. The subsequent occupation of the vicinity by the Portuguese led, in 1549, to the merging of four captaincies under the first governor-general of Brazil, Tomé de Sousa (Sousa, Tomé de), who in the same year founded Salvador as the seat of his government.

The colonization of the territory began in the Recôncavo—that is, in the coastal region—where sugarcane and tobacco were grown for export and other crops raised for the settlers' food. In the semiarid interior, cattle raising was considerably stimulated in the 18th century, when the discovery of gold and gems in the Diamantina Upland attracted more settlers.

When the Empire of Brazil was proclaimed in 1822, Bahia was still controlled by forces loyal to Portugal; but on July 2, 1823, Brazilian troops occupied Salvador, and Bahia became a province of the empire. In 1889, under the republic, Bahia became a state of the Brazilian republic. During the 1890s, a major messianic movement under the charismatic Antônio Conselheiro at Canudos in the arid interior was viewed as a subversive threat to the republic and was bloodily repressed in 1897. This event has been immortalized by famed Peruvian author Mario Vargas Llosa (Vargas Llosa, Mario) as well as many Brazilian writers.

During the 19th century there was a revival of agriculture: it was the golden age for sugarcane, coffee also was grown on a large scale, cotton production increased, and the forests of the south were turned into profitable plantations of cacao. Rubber plantations were developed at the beginning of the 20th century.

The Diamantina Upland and its northern extension, the Tombador Mountains, run north across Bahia from the borders of Minas Gerais and constitute the line of greatest elevation. The Diamantina reaches its maximum elevation in Almas Peak, which is 6,070 feet (1,850 m) in height. From the east and west of this dorsal ridge descend plateaus that vary in elevation between about 650 and 2,600 feet (200 and 800 m) and are characterized by inselbergs (steep-sided, isolated hills that have been left by erosion). The eastern edge of the highlands terminates in the heights overlooking the coastal plain.

The major river is the São Francisco (São Francisco River), which rises in Minas Gerais and flows north across western Bahia before turning eastward in a great curve to form the frontier between Bahia and Pernambuco and between Bahia and Alagoas, on its long way down to the Atlantic. Flowing directly to the coast are several minor rivers, which originate in the Diamantina Upland or in the Espinhaço Mountains of Minas Gerais.

Along Bahia's coastline there are areas where annual rainfall exceeds 55 inches (1,400 mm), as well as sandy stretches on which the Brazilian coconut and the mangabeira rubber tree flourish, while the mud of the estuaries favours mangroves. The sandy clay soil of the narrow coastal plain supports evergreen, broad-leaved tropical forests. The zone of transitional forest to the west consists of deciduous shrubs and smaller plants. In the dry interior zone, which occupies most of the land area and virtually the entire northwestern half of the state, the rainy season is irregular, and the annual rainfall never exceeds 24 inches (610 mm). The dry zone's landscape is open and bare, and plants such as cactus predominate.

Peccary, tapir, and the two-toed sloth live in the forests. In open country the giant armadillo, the scarlet ibis, and the king vulture can be found.

Bahia's population consists of a pronounced mulatto majority, with sizable black and white minorities. Population density varies considerably. The greatest concentrations of Bahia's population reside in the cities and towns of its eastern coastal area, particularly in the Recôncavo. Salvador is the largest city; other urban centres include Ilhéus, Itabuna, Feira de Santana, Vitória da Conquista, Camaçari, Jequié, and Alagoinhas. The arid interior, on the other hand, is sparsely populated and has relatively few towns, with Barreiras in the west and Juazeiro in the north being the most important. Of the total population, a full half live in urban areas.

The language of the people is Portuguese, but it is influenced to some extent by African idioms and slightly by various Indian languages. Roman Catholicism is professed by the overwhelming majority of the population, and the cardinal-archbishop of Salvador is also the primate of Brazil. Protestantism, spiritualism, and other beliefs claim small minorities of the population. Many people practice the rituals of Candomblé, a syncretist religious sect, but declare themselves Roman Catholics.

The standard of living is low. Hygiene is defective, even in urban areas, despite efforts to improve medical services and sanitation. Salvador has two universities, the Federal University of Bahia (1946) and the Catholic University of Salvador (1961).

Among Bahia's mineral resources are petroleum, natural gas, lead, copper, chrome, tin, barite, manganese, magnesite, titanium, hematite, quartz, kaolin, marble, asbestos, and amethyst. There is also a vast hydroelectric potential in the state: the São Francisco River has been harnessed by the Sobradinho, Itaparica, Paulo Afonso, and Xingó dams in Bahia and the neighbouring state of Alagoas.

Crops grown in Bahia include sugarcane, cassava (manioc), soy, corn (maize), cacao, and sisal. Timber is obtained from the forests. Cattle are raised in many parts of the state for their leather and skins as well as meat. Bahia's agriculture was severely threatened by recurring droughts in the latter part of the 20th century, but irrigation has ameliorated this problem. Heavy industry is represented by a petroleum refinery, paper and cellulose manufacturers, cement works and ironworks, and automotive factories. Energy is mostly hydroelectric. Roads and railways stretch across the state but are more concentrated in the Recôncavo, where the Southern Hemisphere's premier concentration of petrochemical industries is centred on the city of Camaçari.

Bahia also has an important tourism industry, with Salvador ranking as one of Brazil's most popular tourist attractions. Among the state's prominent cultural institutions are the Bahia Academy of Letters, the Bahia Geographical and Historical Institute, and the Bahia Institute of Music. The state's major historical figures include the famed abolitionist and essayist Ruy Barbosa, the renowned 20th-century novelist Jorge Amado, and the contemporary national political leader Antônio Carlos Magalhães. Area 218,029 square miles (564,693 square km). Pop. (2006 est.) 13,950,146.