When the colonizers established trading posts and expoited the savages.

<<In what form, and through what types of relations was this subordination secured? It should be recalled that the beginnings of the colonial era were preceded by the establishment of merchant capitalism along the African coasts in the form notably of trading posts. This merchant capital performed the role of a transmission belt marketing tropical products in the metropoles in order to supply the holders of industrial capital. In the metropoles themselves, the integration of industrial capital and finance capital was underway but was still just beginning

Elsewhere, in tropical Africa, the establishment of white settlers on the land was rather limited. The colonial system organized the ***trading economy*** based on the production of tropical products in exchange for manufactured goods. But what should be emphasized is that this was not a free exchange. The peasants were not free to produce what they wanted, but only to produce what the colonizer wanted and on the conditions determined by him. For that every form of constraint was used.
In the beginning the colonial ***trading economy*** rested mainly on the products which could be found on the spot: palm products, timber, shea butter, jute, gum and other products of gathering. Groundnuts and cotton were developed later and were followed by the introduction of new crops previously unknown in much of Africa. Even in 1914, products of gathering still accounted for half the exports of French-ruled Africa. From this period the new products began to take over first place. Throughout the first period the most archaic means - which were also almost without cost - were used to ensure production.
The system of crops and forced labour which remained the general rule led to mediocre results at the level of production which remained unchanged or fell year by year despite the increased resort to force.
It was with the development of cash crops, which offered great possibilities for profits, and in order to increase yields that recourse was had to capital. Thus people began to buy the peasant's crop directly from the peasant, naturally at a price below its value. Compared to the conditions that had prevailed previously and which meant that the village chief was paid a fixed sum for the entire production of the village, this was already progress. The peasants generally saw none of this payment which the village chiefs and their entourage tended to appropriate.
The spread of the use of money and the increase of direct trade with the peasants led to the reduction of compulsory crops; this made it possible to relaunch production, especially of new crops>>