Information about the process and rate of diffusion of cassava comes from historical documents and travelogues. We have tried to summarize our findings in Figure 1. We know, or can speculate, how it was diffused in West and Central Africa, but East Africa is more problematic. This document synthesizes the available information on diffusion of cassava on the continent.

The Portuguese first brought cassava to Africa in the form of flour, or 'farinha'. The Tupinambá Indians of eastern Brazil had taught them techniques of cassava preparation and production, and they had developed a liking for the various processed forms.

Cassava flour was used as a provision for ships plying between Africa, Europe and Brazil. The first mention of cassava cultivation in Africa dates back to 1558. At first, it was cultivated with the sole purpose of provisioning slave ships, until about 1600.

Ross (1975) and Jones (1959) posit that multiple, and more-or-less simultaneous introductions took place at Portuguese trading stations: Fernando Po (Bioko in Equatorial Guinea), the islands of São Tomé and Príncipe, Sierra Leone, and on the Angolan coast between Luanda and the mouth of the Congo River.

Our knowledge of the diffusion of cassava in the interior during the next 250 years is extremely sparse. From the writings of European explorers who penetrated Central Africa in the late 19th century we see that cassava had by then been successfully incorporated into many farming systems.

Cassava spread through Africa by a number of mechanisms. The most important appear to have been initial contacts with the Portuguese-Brazilian culture, through which the crop gained a foothold, by river and possibly overland trade, and by mass migration.

In the late 19th and 20th centuries, colonial administrators encouraged its diffusion and increased cultivation. Cassava's botanical characteristics, such as its capacity to survive and merge in the surrounding bush vegetation and the viability of its cuttings, must have greatly facilitated this spread, as must its tolerance to long periods of neglect that arise through civil unrest.

It is also interesting to note that the consumption of cassava leaves, in frequent rather than sporadic form, was probably an African invention.