First inhabited by pygmies, Congo was later settled by Bantu groups that also occupied parts of present-day Angola, Gabon, and Zaire, forming the basis for ethnic affinities and rivalries among those states. Several Bantu kingdoms--notably those of the Kongo, the Loango, and the Teke--built trade links leading into the Congo River basin. The first European contacts came in the late 15th century, and commercial relationships were quickly established with the kingdoms--trading for slaves captured in the interior. The coastal area was a major source for the transatlantic slave trade, and when that commerce ended in the early 19th century, the power of the Bantu kingdoms eroded.

The area came under French sovereignty in the 1880s. Pierre Savorgnon de Brazza, a French empire builder, competed with agents of Belgian King Leopold's International Congo Association (later Zaire) for control of the Congo River basin. Between 1882 and 1891, treaties were secured with all the main local rulers on the river's right bank, placing their lands under French protection. In 1908, France organized French Equatorial Africa (AEF), comprising its colonies of Middle Congo (modern Congo), Gabon, Chad, and Oubangui-Chari (modern Central African Republic). Brazzaville was selected as the federal capital.

Economic development during the first 50 years of colonial rule in Congo centered on natural resource extraction by private companies. In 1924-34, the Congo-Ocean Railway (CFCO) was built at a considerable human and financial cost, opening the way for growth of the ocean port of Pointe-Noire and towns along its route.

During World War II, the AEF administration sided with Charles DeGaulle, and Brazzaville became the symbolic capital of Free France during 1940-43. The Brazzaville Conference of 1944 heralded a period of major reform in French colonial policy, including the abolition of forced labor, granting of French citizenship to colonial subjects, decentralization of certain powers, and election of local advisory assemblies. Congo benefited from the postwar expansion of colonial administrative and infrastructure spending as a result of its central geographic location within AEF and the federal capital at Brazzaville.

The Loi Cadre (framework law) of 1956 ended dual voting roles and provided for partial self-government for the individual overseas territories. Ethnic rivalries then produced sharp struggles among the emerging Congolese political parties and sparked severe riots in Brazzaville in 1959. After the September 1958 referendum approving the new French Constitution, AEF was dissolved. Its four territories became autonomous members of the French Community, and Middle Congo was renamed the Congo Republic. Formal independence was granted in August 1960.

Congo's first president was Fulbert Youlou, a former Catholic priest from the Pool region in the southeast. He rose to political prominence after 1956, and was narrowly elected president by the National Assembly at independence. Youlou's 3 years in power were marked by ethnic tensions and political rivalry. In August 1963, Youlou was overthrown in a 3-day popular uprising (Les Trois Glorieuses) led by labor elements and joined by rival political parties. All members of the Youlou government were arrested or removed from office. The Congolese military took charge of the country briefly and installed a civilian provisional government headed by Alphonse Massamba-Debat. Under the 1963 Constitution, Massamba-Debat was elected president for a 5-year term and named Pascal Lissouba to serve as Prime Minister. However, President Massamba-Debat's term ended abruptly in August 1968, when Capt. Marien Ngouabi and other army officers toppled the government in a coup. After a period of consolidation under the newly formed National Revolutionary Council, Major Ngouabi assumed the presidency on December 31, 1968. One year later, President Ngouabi proclaimed Congo to be Africa's first "people's republic" and announced the decision of the National Revolutionary Movement to change its name to the Congolese Labor Party (PCT).

On March 18, 1977, President Ngouabi was assassinated. Although the persons accused of shooting Ngouabi were tried and some of them executed, the motivation behind the assassination is still not clear. An 11-member Military Committee of the Party (CMP) was named to head an interim government with Colonel (later General) Joachim Yhomby-Opango to serve as President of the Republic. Accused of corruption and deviation from party directives, Yhomby-Opango was removed from office on February 5, 1979, by the Central Committee of the PCT, which then simultaneously designated Vice President and Defense Minister Col. Denis Sassou-Nguesso as interim President. The Central Committee directed Sassou-Nguesso to take charge of preparations for the Third Extraordinary Congress of the PCT, which proceeded to elect him President of the Central Committee and President of the Republic. Under a congressional resolution, Yhomby-Opango was stripped of all powers, rank, and possessions and placed under arrest to await trial for high treason. He was released from house arrest in late 1984 and ordered back to his native village of Owando.

After two decades of turbulent politics bolstered by Marxist-Leninist rhetoric, and with the collapse of the Soviet Union, the Congolese gradually moderated their economic and political views to the point that, in 1992, Congo completed a transition to multi-party democracy. Ending a long history of one-party Marxist rule, a specific agenda for this transition was laid out during Congo's national conference of 1991 and culminated in August 1992 with multi-party presidential elections. Sassou-Nguesso conceded defeat and Congo's new president, Prof. Pascal Lissouba, was inaugurated on August 31, 1992.

Congolese democracy experienced severe trials in 1993 and early 1994. President Lissouba dissolved the National Assembly in November 1992, calling for new elections in May 1993. The results of those elections were disputed, touching off violent civil unrest in June and again in November. In February 1994, all parties accepted the decisions of an international board of arbiters, and the risk of largescale insurrection subsided.

However, Congo's democratic progress was derailed in 1997. As presidential elections scheduled for July 1997 approached, tensions between the Lissouba and Sassou camps mounted. When on June 5, President Lissouba's government forces surrounded Sassou's compound in Brazzaville with armored vehicles, Sassou ordered his militia to resist. Thus began a 4-month conflict that destroyed or damaged much of Brazzaville. In early October, Angolan troops invaded Congo on the side of Sassou and, in mid-October, the Lissouba government fell. Soon thereafter, Sassou declared himself President and named a 33-member government.

In January 1998, the Sassou regime held a National Forum for Reconciliation to determine the nature and duration of the transition period. The Forum, tightly controlled by the government, decided elections should be held in about 3 years, elected a transition advisory legislature, and announced that a constitutional convention would finalize a draft Constitution. However, the eruption in late 1998 of fighting between Sassou's government forces and a pro-Lissouba and pro-Kolelas armed opposition disrupted the transition to democracy. This new violence also closed the economically vital Brazzaville-Pointe Noire railroad; caused great destruction and loss of life in southern Brazzaville and in the Pool, Bouenza, and Niari regions; and displaced hundreds of thousands of persons. In November and December 1999, the government signed agreements with representatives of many, though not all, of the rebel groups.

The December accord, mediated by President Omar Bongo of Gabon, called for follow-on, inclusive political negotiations between the government and the opposition. During the years 2000-01, Sassou-Nguesso's government conducted a national dialogue (Dialogue Sans Exclusif), in which the opposition parties and the government agreed to continue on the path to peace. Ex-President Lissouba and ex-Prime Minister Kolelas refused to agree and have been exiled for all practical purposes. They were tried in absentia and convicted in Brazzaville of charges ranging from treason to misappropriation of government funds. Ex-militiamen were granted amnesty, and many were provided microloans to aid their reinsertion into civil society. Not all opposition members participated. One group, referred to as "Ninjas," actively opposed the government in a low-level guerrilla war in the Pool region of the country. Other members of opposition parties have returned and have opted to participate to some degree in political life. A new Constitution was drafted in 2001, approved by the provisional legislature (National Transition Council), and approved by the people of Congo in a national referendum in January 2002. Presidential elections were held in March 2002, and Sassou-Nguesso was declared the winner. Legislative elections were held in May and June 2002. In March 2003 the government signed a peace accord with the Ninjas, and the country has remained stable and calm since the signing. Internally displaced person are returning to the Pool region.