When the Portuguese introduced the crop into the Kingdom of Kongo, near the mouth of the Congo River, it was adopted as part of a process of cultural assimilation, consciously promoted by the King. Portuguese settlers and Africans both began to grow cassava.

One of the first accounts of cassava cultivation in Central Africa comes from Samuel Brun in 1611. He described flour preparation from bitter cassava roots at Loango. It is probable that cassava had already been cultivated for some years in Loango before this date. In 1620, Bras Correa witnessed cassava cultivation 'in the Brasilian manner' by Portuguese settlers at Mpinda at the mouth of the Congo River.

In 1640, the Dutch explorer Dapper mentioned Luanda (Angola) as the primary production area of cassava, giving as reasons for its cultivation:

In 1687, Cavazzi mentions cassava as the food for both poor and rich in the Kongo Kingdom (although formerly millet and sorghum were preferred to cassava). In 1704, Lucques notes that maize had been replaced by cassava as the primary staple crop.

By the middle of the 18th century, cassava was the principal food crop among the Kakongo living north of the mouth of the Congo River, and, in 1787, in the Kongo Kingdom and in Loango.

Early dissemination of cassava to inland areas, at least in precolonial Congo, was carried out solely by Africans. Europeans entered the interior only a long period afterwards, since the Congo River could not be entered from the sea.

It is assumed that cassava initially expanded throughout the territories of the western groups of the central Bantu through trade. It is likely that cassava was transported from the mouth of the Congo in a south-eastern direction, following long-distance trade routes. Its spread was probably very slow.

The Lamba, living in what is now the extreme south-east of Zaire, at the end of the trade route from Bié and Silva Porto (Nova Lisboa, Angola), knew cassava in 1852. Wood (1985) notes that cassava was only introduced to the upper Zambezi in the 1830s, by Mbunda migrants from north-east Angola, where it was already known early in the 17th century.

Pasch (1980) concludes, from linguistic studies based on the similarity of local names for cassava on the trade routes, that several of these routes accounted for the spread of the crop. The first route extended from Angola to Mozambique, while another route led probably from central Zaire to northern Zimbabwe.

A third route connected the Lozi (on the borders of present-day Zimbabwe) to the Tonga in Zambia, as is indicated for example by the fact that the term 'mwanja' (cassava) has been adapted from Lozi in Tonga. Dates of diffusion are hard to ascertain by using linguistic evidence such as this.

In contrast, the spread of cassava towards the north-east, along the Congo and its tributaries, seems to have been much faster. Riverine trade has been an obvious mechanism, but what were the reasons for its adoption? Jones (1957) hypothesizes that cassava was able to fill an important niche in humid forest agriculture, where few crops were properly adapted to the environment. He attributed this situation to the recency of occupation of much of the forest by Bantu peoples, who originated in savanna areas, and who lacked a well-adapted staple for the rain-forest.

In addition, he noted that many of the peoples of the Congo Basin were accustomed to the cultivation of bananas, a crop which required similar cultural practices, had similar harvest periods and required similar processing techniques to cassava. However, this only holds for those ethnic groups that had already developed some form of semi-sedentary shifting cultivation, and not for hunters and gatherers.

Cassava seems to have replaced millet, yam and plantain as the principal staple in most areas along the Congo River, resulting in a boost of trade in agricultural products. In 1698, cassava was already the staple food at the Stanley (Malebo) Pool, near Kinshasa. From there, it spread upriver and inland. Harms (1981) quotes as reasons for its introduction:

Cassava consumption was widespread amongst the river people. Cassava was especially suited to take along on trips, presumably in processed form such as 'chikwangue', and constituted a balanced diet in combination with fish.

The trade in cassava rapidly took on huge proportions, since the river people did not produce sufficient cassava for their own consumption.

At the end of the 19th century, one observer measured a daily shipment of 40 tons/day along the Alima River in the present-day Congo republic. Others measured 150 tons/week and 14-17 tons/day. Some tribes specialized in the trade of cassava and founded markets along the rivers. Malebo Pool was a regional center for the trade, cassava being transported from a radius of 250 km (and sometimes more) around this area.

Evidence from 19th century Francophone explorers in Central Africa supports the hypothesis of riverine diffusion. Prioul (1957), in a review of the literature on the Central African Republic, cites the riverine relations of the Oubangui as hastening the spread of cassava.

By the end of the 19th century, it was well established amongst the Oubangui, Oudda, N'dris and Gbaya (Nana Membere).

There are indications that, in the 19th century, north of Bangui and in the savannas, cassava may have been temporarily superseded as the principal contemporary staple by bananas and, in the savanna, by cereals.

However, during the present century, both cassava and maize have come to dominate agriculture in northern Congo (republic) and Central African Republic, replacing both bananas and traditional cereals such as bulrush millet.

Cassava was also introduced in Francophone Africa along coastal Cameroon, Equatorial Guinea and Gabon. Here, too, it spread along fluvial arteries, particularly along the Ogooué River to the interior of Gabon. From the Congo, it diffused to the eastern parts of these territories along the Sangha River, as far as Yokadouma in Cameroon during the 19th century.

Jones suggests that the diffusion of cassava in the interior of Cameroon, Gabon and Equatorial Guinea has occurred only during the 20th century. More recent evidence allows us to modify this picture. It is true that, in early sources of 1640, cassava was not mentioned as a food crop in the Estuaire (hinterland of Libreville) and, in 1682, it is not referred to as being in Cap Lopez, but it is very probable that cassava became more important after 1760 in Gabon, when the slave trade began to flourish.

Eventually, it became the principal food crop in the Estuaire in 1865, in Moyen-Ogooué (south of Libreville) and among the Fang. It had certainly become a widely cultivated crop in the region of Franceville in 1875. However, in some inland areas, such as Ogooué-Maritime and N'Gounié, it was seldom found.

In 1850, cassava was noted by Barth (a German traveler) in north Cameroon among the Fulani, who were probably responsible for the spread of the crop in that area. Most names for cassava in surrounding languages are related to the Fulani or Fulfulde name 'mbai'.

We may conclude that cassava must have spread by river throughout much of Central Africa during the 18th and 19th centuries. It was present on the western shores of Lakes Nyasa and Tanganyika in the second half of the 19th century when Europeans first explored the area.

In some areas, more widespread diffusion to the inter-fluves appears to have been a slower process, being dependent upon trade and hindered by political relations and possibly warfare. Prior to the imposition of European administrations, migration was probably the main means of diffusion of cassava across watersheds.

Both Wood (1985) and Prioul (1957) mention its introduction to new areas through migration. Prioul also underlines cassava's importance in areas subject to belligerent incursions in the Central African Republic: marauders could do far less damage to cassava tubers than they could to cereal crops.

More recent recurrences of this situation are the civil wars of Zaire in the early 1960s and Mozambique in the 1980s, where cassava often became the sole food source as a result of the disruption of farming activities by war.