Little is known of the earliest history of Nigeria. By c.2000 b.c. most of the country was sparsely inhabited by persons who had a rudimentary knowledge of raising domesticated food plants and of herding animals. From c.800 b.c. to c.a.d. 200 the Nok culture (named for the town where archaeological findings first were made) flourished on the Jos Plateau; the Nok people made fine terra-cotta sculptures and probably knew how to work tin and iron. The first important centralized state to influence Nigeria was Kanem-Bornu, which probably was founded in the 8th cent. a.d., to the north of Lake Chad (outside modern Nigeria). In the 11th cent., by which time its rulers had been converted to Islam, Kanem-Bornu expanded south of Lake Chad into present-day Nigeria, and in the late 15th cent. its capital was moved there.

Beginning in the 11th cent. seven independent Hausa city-states were founded in N Nigeria—Biram, Daura, Gobir, Kano, Katsina, Rano, and Zaria. Kano and Katsina competed for the lucrative trans-Saharan trade with Kanem-Bornu, and for a time had to pay tribute to it. In the early 16th cent. all of Hausaland was briefly held by the Songhai Empire. However, in the late 16th cent., Kanem-Bornu replaced Songhai as the leading power in N Nigeria, and the Hausa states regained their autonomy. In southwest Nigeria two states—Oyo and Benin—had developed by the 14th cent.; the rulers of both states traced their origins to Ife, renowned for its naturalistic terra-cotta and brass sculpture. Benin was the leading state in the 15th cent. but began to decline in the 17th cent., and by the 18th cent. Oyo controlled Yorubaland and also Dahomey. The Igbo people in the southeast lived in small village communities.

In the late 15th cent. Portuguese navigators became the first Europeans to visit Nigeria. They soon began to purchase slaves and agricultural produce from coastal middlemen; the slaves had been captured further inland by the middlemen. The Portuguese were followed by British, French, and Dutch traders. Among the Igbo and Ibibio a number of city-states were established by individuals who had become wealthy by engaging in the slave trade; these included Bonny, Owome, and Okrika.

There were major internal changes in Nigeria in the 19th cent. In 1804, Usuman dan Fodio (1754-1817), a Fulani and a pious Muslim, began a holy war to reform the practice of Islam in the north. He soon conquered the Hausa city-states, but Bornu, led by Muhammad al-Kanemi (also a Muslim reformer) until 1835, maintained its independence. In 1817, Usuman dan Fodio's son, Muhammad Bello (d.1837) established a state centered at Sokoto, which controlled most of N Nigeria until the coming of the British (1900-1906). Under both Usuman dan Fodio and Muhammad Bello, Muslim culture, and also trade, flourished in the Fulani empire. In Bornu, Muhammad al-Kanemi was succeeded by Umar (reigned 1835-80), under whom the empire disintegrated.

In 1807, Great Britain abandoned the slave trade; however, other countries continued it until about 1875. Meanwhile, many African middlemen turned to selling palm products, which were Nigeria's chief export by the middle of the century. In 1817 a long series of civil wars began in the Oyo Empire; they lasted until 1893 (when Britain intervened), by which time the empire had disintegrated completely.

In order to stop the slave trade there, Britain annexed Lagos in 1861. In 1879, Sir George Goldie gained control of all the British firms trading on the Niger, and in the 1880s he took over two French companies active there and signed treaties with numerous African leaders. Largely because of Goldie's efforts, Great Britain was able to claim S Nigeria at the Conference of Berlin (see Berlin, Conference of) held in 1884-85.

In the following years, the British established their rule in SW Nigeria, partly by signing treaties (as in the Lagos hinterland) and partly by using force (as at Benin in 1897). Jaja, a leading African trader based at Opobo in the Niger delta and strongly opposed to European competition, was captured in 1887 and deported. Goldie's firm, given (1886) a British royal charter, as the Royal Niger Company, to administer the Niger River and N Nigeria, antagonized Europeans and Africans alike by its monopoly of trade on the Niger; in addition, it was not sufficiently powerful to gain effective control over N Nigeria, which was also sought by the French.

In 1900 the Royal Niger Company's charter was revoked and British forces under Frederick Lugard began to conquer the north, taking Sokoto in 1903. By 1906, Britain controlled Nigeria, which was divided into the Colony (i.e., Lagos) and Protectorate of Southern Nigeria and the Protectorate of Northern Nigeria. In 1914 the two regions were amalgamated and the Colony and Protectorate of Nigeria was established.

The administration of Nigeria was based on a system devised by Lugard and called "indirect rule"; under this system, Britain ruled through existing political institutions rather than establishing a wholly new administrative network. In some areas (especially the southeast) new African officials (resembling the traditional rulers in other parts of the country) were set up; in most cases they were not accepted by the mass of the people and were able to rule only because British power stood behind them. All important decisions were made by the British governor, and the African rulers, partly by being associated with the colonialists, soon lost most of their traditional authority. Occasionally (as in Aba in 1929) discontent with colonial rule flared into open protest.

Under the British, railroads and roads were built and the production of cash crops, such as palm nuts and kernels, cocoa, cotton, and peanuts, was encouraged. The country became more urbanized as Lagos, Ibadan, Kano, Onitsha, and other cities grew in size and importance. From 1922, African representatives from Lagos and Calabar were elected to the legislative council of Southern Nigeria; they constituted only a small minority, and Africans otherwise continued to have no role in the higher levels of government. Self-help groups organized on ethnic lines were established in the cities. A small Western-educated elite developed in Lagos and a few other southern cities.

In 1947, Great Britain promulgated a constitution that gave the traditional authorities a greater voice in national affairs. The Western-educated elite was excluded, and, led by Herbert Macaulay and Nnamdi Azikiwe, its members vigorously denounced the constitution. As a result, a new constitution, providing for elected representation on a regional basis, was instituted in 1951.

Three major political parties emerged—the National Council of Nigeria and the Cameroons (NCNC; from 1960 known as the National Convention of Nigerian Citizens), led by Azikiwe and largely based among the Igbo; the Action Group, led by Obafemi Awolowo and with a mostly Yoruba membership; and the Northern People's Congress (NPC), led by Ahmadu Bello and based in the north. The constitution proved unworkable by 1952, and a new one, solidifying the division of Nigeria into three regions (Eastern, Western, and Northern) plus the Federal Territory of Lagos, came into force in 1954. In 1956 the Eastern and Western regions became internally self-governing, and the Northern region achieved this status in 1959.

With Nigerian independence scheduled for 1960, elections were held in 1959. No party won a majority, and the NPC combined with the NCNC to form a government. Nigeria attained independence on Oct. 1, 1960, with Abubakar Tafawa Balewa of the NPC as prime minister and Azikiwe of the NCNC as governor-general; when Nigeria became a republic in 1963, Azikiwe was made president.

The first years of independence were characterized by severe conflicts within and between regions. In the Western region, a bloc of the Action Group split off (1962) under S. I. Akintola to form the Nigerian National Democratic party (NNDP); in 1963 the Mid-Western region (whose population was mostly Edo) was formed from a part of the Western region. National elections late in 1964 were hotly contested, with an NPC-NNDP coalition (called the National Alliance) emerging victorious.

In Jan., 1966, Igbo army officers staged a successful coup, which resulted in the deaths of Federal Prime Minister Balewa, Northern Prime Minister Ahmadu Bello, and Western Prime Minister S. I. Akintola. Maj. Gen. Johnson T. U. Aguiyi-Ironsi, an Igbo, became head of a military government and suspended the national and regional constitutions; this met with a violent reaction in the north. In July, 1966, a coup led by Hausa army officers ousted Ironsi (who was killed) and placed Lt. Col. Yakubu Gowon at the head of a new military regime. In Sept., 1966, many Igbo living in the north were massacred.

Gowon attempted to start Nigeria along the road to civilian government but met determined resistance from the Igbo, who were becoming increasingly fearful of their position within Nigeria. In May, 1967, the Eastern parliament gave Lt. Col. Chukwuemeka O. Ojukwu, the region's leader, authority to declare the region an independent republic. Gowon proclaimed a state of emergency, and, as a gesture to the Igbos, redivided Nigeria into 12 states (including one, the East-Central state, that comprised most of the Igbo people). However, on May 30, Ojukwu proclaimed the independent Republic of Biafra, and in July fighting broke out between Biafra and Nigeria.

Biafra made some advances early in the war, but soon federal forces gained the initiative. After much suffering, Biafra capitulated on Jan. 15, 1970, and the secession ended. The early 1970s were marked by reconstruction in areas that were formerly part of Biafra, by the gradual reintegration of the Igbo into national life, and by a slow return to civilian rule.

Spurred by the booming petroleum industry, the Nigerian economy quickly recovered from the effects of civil war and made impressive advances. Nonetheless, inflation and high unemployment remained, and the oil boom led to government corruption and uneven distribution of wealth. Nigeria joined the Organization of Petroleum Exporting Countries in 1971. The prolonged drought that desiccated the Sahel region of Africa in the early 1970s had a profound effect on N Nigeria, resulting in a migration of peoples into the less arid areas and into the cities of the south.

Gowon's regime was overthrown in 1975 by Gen. Murtala Muhammad and a group of officers who pledged a return to civilian rule. In the mid-1970s plans were approved for a new capital to be built at Abuja, a move that drained the national economy. Muhammad was assassinated in an attempted coup one year after taking office and succeeded by Gen. Olusegun Obasanjo. In a crisis brought on by rapidly falling oil revenues, the government restricted public opposition to the regime, controlled union activity and student movements, nationalized land, and increased oil industry regulation. Nigeria sought Western support under Obasanjo while supporting African nationalist movements.

In 1979 elections were held under a new constitution, bringing Alhaji Shehu Shagari to the presidency. Relations with the United States reached a new high in 1979 with a visit by President Jimmy Carter. The government expelled thousands of foreign laborers in 1983, citing social disturbances as the reason. The same year, Shagari was reelected president but overthrown after only a few months in office.

In 1985 a coup led by Maj. Gen. Ibrahim Babangida brought a new regime to power, along with the promise of a return to civilian rule. A new constitution was promulgated in 1990, which set national elections for 1992. Babangida annulled the results of that presidential election, claiming fraud. A new election in 1993 ended in the apparent presidential victory of Moshood Abiola, but Babangida again alleged fraud. Soon unrest led to Babangida's resignation. Ernest Shonekan, a civilian appointed as interim leader, was forced out after three months by Gen. Sani Abacha, a long-time ally of Babangida, who became president and banned all political institutions and labor unions. In 1994, Abiola was arrested and charged with treason.

In 1995, Abacha extended military rule for three more years, while proposing a program for a return to civilian rule after that period; his proposal was rejected by opposition leaders, but five political parties were established in 1996. The Abacha regime drew international condemnation in late 1995 when Ken Saro-Wiwa, a prominent writer, and eight other human-rights activists were executed; the trial was condemned by human-rights groups and led to Nigeria's suspension from the Commonwealth of Nations. Also in 1995, a number of army officers, including former head of state General Obasanjo, were arrested in connection with an alleged coup attempt. In 1996, Kudirat Abiola, an activist on behalf of her imprisoned husband, was murdered.

Abacha died suddenly in June, 1998, and was succeeded by Gen. Abdulsalam Abubakar, who immediately freed Obasanjo and other political prisoners. Riots followed the announcement that Abiola had also died unexpectedly in July, 1998, while in detention. Abubakar then announced an election timetable leading to a return to civilian rule within a year. All former political parties were disbanded and new ones formed. A series of local, state, and federal elections were held between Dec., 1998, and Feb., 1999, culminating in the presidential contest, won by General Obasanjo. The elections were generally deemed fair by international monitors. The People's Democratic party (PDP; the centrist party of General Obasanjo) dominated the elections; the other two leading parties were the Alliance for Democracy (a Yoruba party of the southwest, considered to be progressive), and the All People's party (a conservative party based in the north).

Following Obasanjo's inauguration on May 29, 1999, Nigeria was readmitted to the Commonwealth. The new president said he would combat past and present corruption in the Nigerian government and army and develop the impoverished Niger delta area. Although there was some progress economically, government and political corruption remained a problem. The country also was confronted with renewed ethnic and religious tension. The latter was in part a result of the institution of Islamic law in Nigeria's northern states, and led to violence that has been an ongoing problem since the return of civilian rule. Army lawlessness was a problem as well in some areas. A small success was achieved in Apr., 2002, when Abacha's family agreed to return $1 billion to the government; the government had sought an estimated $4 billion in looted Nigerian assets.

In Mar., 2003, the Ijaw, accusing the Itsekiri, government, and oil companies of economic and political collusion against them, began militia attacks against Itsekiri villages and oil facilities in the Niger delta, leading to a halt in the delta's oil production for several weeks and military intervention by the government. The presidential and earlier legislative elections in Apr., 2003, were won by President Obasanjo and his party, but the results were marred by vote rigging and some violence. The opposition protested the results, and unsuccessfully challenged the presidential election in court. The Ijaw-Itsekiri conflict continued into 2004, but a peace deal was reached in mid-June. The Ijaw backed out of the agreement, however, three weeks later. Christian-Muslim tensions also continued to be a problem in 2004, with violent attacks occurring in Kebbi, Kano, and Plateau states.

Obasanjo's government appeared to move more forcefully against government corruption in early 2005. Several government ministers were fired on corruption charges, and the senate speaker resigned after he was accused of taking bribes. A U.S. investigation targeted Nigeria's vice president the same year, and Obasanjo himself agreed to be investigated by the Nigerian financial crimes commission when he was accused of corruption by Orji Uzor Kalu, the governor of Abia and a target of a corruption investigation. Ijaw militants again threatened Niger delta oil operations in Sept., 2005, and several times in subsequent years, resulting in cuts in Nigeria's oil production as large as 25% at times. Since early 2006 the Niger delta area has seen an increase in kidnappings of foreign oil workers and attacks on oil operations; the resulting government focus on protecting oil facilities allowed criminal gangs to expand their influence in populated areas there. In Oct., 2005, the government reached an agreement to pay off much of its foreign debt at a discount, a process that was completed in Apr., 2006.

The end of 2005 and early 2006 saw increased contention over whether to amend the constitution to permit the president and state governors to run for more than two terms. The idea had been rejected in July, 2005, by a national political reform conference, but senators reviewing the conference's proposals indicated they supported an end to term limits. The change was opposed by Vice President Atiku Abubakar, but other PDP leaders who objected were removed from their party posts. A census—a contentious event because of ethnic and religious divisions in Nigeria—was taken in Mar., 2006, but the head count was marred by a lack of resources and a number of violent clashes, and many Nigerians were believed to have been left uncounted. In May the Nigerian legislature ended consideration of a third presidential term when it became clear that there was insufficient support for amending the constitution. Nigeria agreed in June, 2006, to turn over the Bakassi peninsula to Cameroon after a two-year transition period; the region was finally ceded in Aug., 2008.

In July the vice president denied taking bribes from a U.S. congressman, but in September the president called for the Nigerian senate to remove the vice president from office for fraud, based on an investigation by the Economic and Financial Crimes Commission (EFCC). The senate agreed to investigate the charges, and the PDP suspended the vice president, blocking him from seeking the party's presidential nomination. Abubakar counteraccused Obasanjo of corruption. The EFCC was also investigating most of Nigeria's state governors, but the commission itself was tainted by charges that it was used for political retaliation by Obasanjo and his allies. Several state governors were impeached by legally unsound proceedings, moves that were seen as an attempt by Obasanjo to tighten his control prior to the 2007 presidential election.

When the vice president accepted (Dec., 2006) the presidential nomination of a group of opposition parties, the president accused him of technically resigning and sought to have him removed, an action Abubakar challenged in court; the government backed down the following month, and the courts later sided with Abubakar. In Jan., 2007, the results of the 2006 census were released, and they proved as divisive as previous Nigerian censuses. The census showed that the largely Muslim north had more inhabitants than the south, and many southern political leaders vehemently rejected the results.

In February, the EFCC declared Abubakar and more than 130 other candidates for the April elections unfit due to corruption, and the election commission barred those candidates from running. Abubakar fought the move in court, but the ruling was not overturned until days before the presidential election. The state elections were marred by widespread and blatant vote fraud and intimidation, but the election commission certified nearly all the results, handing gubernatorial victories to the PDP in 27 states. In the presidential election, Umaru Yar'Adua, the relatively unknown governor of Katsina state who was hand-picked by Obasanjo to be the PDP candidate, was declared the winner with 70% of the vote, but fraud and intimidation were so blatant that EU observers called the election a "charade" and the president was forced to admit it was "flawed." Nonetheless, Yar'Adua's inauguration (May) marked the first transition of power between two elected civilian presidents in Nigeria's post-colonial history.

Yar'Adua subsequently moved to reorganize and reform the national petroleum company, but those efforts stalled, as did action to fight government corruption. The federal government did not, however, interfere with challenges in the courts to state elections. In Dec., 2008, challenges in the courts to Yar'Adua's election came to an end when the supreme court ruled that opposition lawyers had not provided sufficient evidence to annul the vote.

In Feb., 2009, KBR, a U.S. company, pleaded guilty in U.S. court to giving $180 million in bribes to Nigerian officials to obtain a contract to build a liquefied natural gas plant. A significant army offensive against Niger delta militants that began in May, 2009, provoked an increased round of attacks against oil facilities, particularly pipelines. At the same time, however, Yar'Adua offered (June) amnesty to militants who lay down their weapons by Oct. 4, and many militants ultimately accepted the amnesty, though some did not. Subsequent slow progress by the government led to increased tensions in 2010. In July, 2009, Boko Haram, an extremist Islamist sect, launched attacks against the government in NE Nigeria after several leaders were arrested; the subsequent fighting was especially fierce in Maiduguri, where the group's headquarters was destroyed and some 700 died. The group began a new series of attacks in Sept., 2010, that continued into subsequent years, with the attacks become more significant beginning in mid-2011.

The president traveled to Saudi Arabia in Nov., 2009, to seek medical treatment. As his stay there prolonged into 2010 many prominent Nigerians called for executive powers to be transferred on an interim basis to the vice president, Goodluck Jonathan, but the president did not initiate the constitutional process necessary for it to happen. In Feb., 2010, the National Assembly unanimously voted to make Jonathan acting president, but the lack of a formal letter from the president notifiying the Assembly of his absence raised constitutional issues. Jonathan remained acting president after Yar'Adua returned later in the month, and succeeded him as president when Yar'Adua died in May.

Jonathan's subsequent decision to run for a presidential term in his own right threatened to split the PDP, which had alternated fielding northern and southern presidential candidates. In Dec., 2010, however, he won the support of most of the state governors who were members of the PDP, and the following month the PDP nominated him for the presidency. In Sept., 2010, one faction of Niger delta militants announced an end to their cease-fire, and the group subsequently set off car bombs in Abuja during an independence day parade on October 1.

The Apr., 2011, elections were won by Jonathan and the PDP. Jonathan won 57% of the vote, but overwhelmingly majorities in a number of southern states led to charges of vote rigging. The opposition candidates challenged the results, and in some northern states, where support for the opposition was strong, there were riots after the results were announced. International observers, however, generally described the presidential election as the country's freest and fairest in many years. In the National Assembly elections, the PDP won with a reduced majority in both houses, and it also lost control of a number of governorships in the subsequent gubernatorial elections. By the first half of 2012 the increasingly violent, ongoing insurgency by the Islamic militant group Boko Haram was stoking sectarian tensions and worsening the economic situation in the already economically stagnant N Nigeria; the situation had also led to significantly larger government expenditures on security, diverting money from other needs.