Abstract : This thesis is divided into two parts. The first presents anethnographic approach of key elements of social organization among theManxineru of the Upper Iaco River. It seeks to sketch a logic of actionand relationship, and then describes how this logic operates in theformation of ensembles and villages. The second compiles and contrastsdistinct historical "episodes", originating from the historical archive andthe record of narratives told by manxineru people. The aim of this part isto shed light on how the autonomy of groups of people has been lost andreconquered throughout recent history, from the invasion of theheadwaters of the rivers by the exploiters of rubber, through theestablishment of people on the margins of seringais and farms, when theindigenous land is demarcated, a moment perceived as liberation and aresumption of the proper modes of social organization.