Pre-colonial

The Portuguese explorer Diogo Cão reached the mouth of the Congo in 1484. Commercial relationships quickly grew between the inland Bantu kingdoms and European merchants who traded various commodities, manufactured goods, and people captured from the hinterlands. After centuries as a major hub for transatlantic trade, direct European colonization of the Congo river delta began in the late 19th century, subsequently eroding the power of the Bantu societies in the region.

French colonial era

The area north of the Congo River came under French sovereignty in 1880 as a result of Pierre de Brazza's treaty with King Makoko of the Bateke. This Congo Colony became known first as French Congo, then as Middle Congo in 1903. In 1908, France organized French Equatorial Africa (AEF), comprising Middle Congo, Gabon, Chad, and Oubangui-Chari (the modern Central African Republic). The French designated Brazzaville as the federal capital. Economic development during the first 50 years of colonial rule in Congo centered on natural-resource extraction. The methods were often brutal: construction of the Congo–Ocean Railroad following World War I has been estimated to have cost at least 14,000 lives.

Following the revision of the French constitution that established the Fifth Republic in 1958, the AEF dissolved into its constituent parts, each of which became an autonomous colony within the French Community. During these reforms, Middle Congo became known as the Republic of the Congo in 1958 and published its first constitution in 1959. Antagonism between the pro-Opangault Mbochis and the pro-Youlou Balalis resulted in a series of riots in Brazzaville in February 1959, which the French Army subdued.

Post-independence era

The Republic of the Congo received full independence from France on 15 August 1960. Fulbert Youlou ruled as the country's first president until labour elements and rival political parties instigated a three-day uprising that ousted him. The Congolese military took charge of the country briefly and installed a civilian provisional government headed by Alphonse Massamba-Débat.

Resentment and bitterness between the Baali and the Mbochi peoples brought upheaval in Brazzaville (February 1959). The French army arrived to quell the turmoil. The highly controversial leader, Abbé Fulbert Youlou, the first black mayor to be elected in French Equatorial Africa and "the first president of our country" was overthrown in August 1963 during Les Trois Glorieuses which is a reference to the 1830 revolution of the same name against Charles X of France.

Pascal Lissouba, who became Congo's first elected president (1992–1997) during the period of multi-party democracy, attempted to implement economic reforms with IMF backing to liberalize the economy. In June 1996 the IMF approved a three-year SDR69.5m (US$100m) enhanced structural adjustment facility (ESAF) and was on the verge of announcing a renewed annual agreement when civil war broke out in Congo in mid-1997.