Guinea-Bissau emerged from the Portuguese-occupied stretch of West Africa after the agreement of 1886 which fixed colonial boundaries in the region. The Portuguese had been present in the region since the mid-15th century and had established a substantial slave trade there. Guinea-Bissau was administered jointly with the Cape Verde islands until 1879, after which it was treated as a separate entity known as Portuguese Guinea until independence. Like other Portuguese colonies, Guinea-Bissau suffered a protracted war of independence between 1963 and 1974, led on the rebel side by Amilcar Cabral, a highly respected figure inside the country. The independence of the Republic of Guinea-Bissau was proclaimed in 1973, with Cabral as President of the State Council.
In 1974 a military coup in Portugal, itself partly the result of heavy losses sustained by the army in Guinea-Bissau, brought about a sudden withdrawal of the colonial authorities. In September that year, Portugal formally recognised the independence of Guinea-Bissau. The leader of the Partido Africano da Independencia da Guine e Cabo Verde (PAIGC), who has held office since 1978, was Joao Vieira, formerly chief of the armed forces. Guinea-Bissau functioned as a typical one-party state until the beginning of the 1990s when the government began a process of political reform which led to multi-party elections being held in 1994. The PAIGC secured a clear majority in the National People's Assembly while Vieira secured the presidency at the run-off stage.
The late 1990s saw Guinea-Bissau consumed by economic decline and a seriously deteriorating security situation. The latter began with prolonged dispute with neighbouring Senegal. This began in 1989 with a dispute over maritime borders: this was settled by a bilateral agreement signed in October 1993. But relations once again broke down in February 1995, after the Senegalese air force bombed the village of Ponta Rosa in Guinea-Bissau. Again, diplomatic mediation quelled the dispute.
The peace was short-lived: in June 1998, full-scale civil war broke out in Guinea-Bissau. The Vieira government faced a rebellion led by Brigadier Ansumane Mane, an army chief who had been sacked on suspicion of smuggling arms to rebels battling for autonomy in Senegal's southern province of Casamance. Senegal and Guinea both sent troops to Vieira's aid, and attempts to broker peace were led by France, Libya and the Gambia. Vieira, however, declared himself uninterested in talks, and determined to drive the rebels out. The two sides reached a temporary truce, brokered by the Nigerians, in November 1998, but fighting again broke out in May 1999. This time, the rebels under General Ansumane Mane, proved strong enough to oust Vieira, who sought asylum in Portugal. The new military administration promised an early return to civilian government. This took place with the holding of elections in January 2000, at which the Partido para a Renovacao Social (PRS) defeated the old PAIGC and another new party, the Resistencia da Guine-Bissau (RGB) for the presidency, and also became the largest single party (though without an overall majority) in the National Assembly. Kumba Iala, the PRS leader who now holds the presidency, was almost immediately confronted by yet another attempted military coup. It was launched in November 2000 by General Mane and his supporters who felt that the new Government was ethnically and tribally biased. Although forces loyal to the new Government managed to defeat General Mane's forces, the rebels enjoy widespread support in the army and the population at large. Guinea-Bissau is now in danger of becoming another casualty of the mayhem spreading across West Africa.

Under the terms of the revised 1984 Constitution, legislative power is vested in the National People's Assembly, which comprises 102 members, popularly elected for a term of four years. Executive power is vested in the President of the Republic, who is head of state and who governs with the assistance of an appointed Council of Ministers, led by the Prime Minister. The President is directly elected for a term of five years.