The article attempts to explain one of the reasons for the political instability that many countries in the world and, in particular, Africa face. This is the problem of multiethnicity and various forms of its instrumentalization to destabilize the country. the author of the article will try to demonstrate the involvement of internal (political) actors but also the place of Western institutions such as France as well as other external regional and international actors such as the UN and certain countries in the region. The purpose of this article is to show that the ethnic factor is one of the political means of weakening and segmenting former African colonies by Western powers. It is important and necessary to clarify the following tasks to try to achieve this goal: consider the colonial policy of France towards African states; identify the main ethnic groups and analyze their actions to destabilize the state; prove the cooperation and support of Western powers to these ethnic groups. The hypothesis put forward by the author is that the destabilization of the state of Mali associated with ethno-separatism and terrorism finds support mainly from Western powers and, in particular, from the former colonialist France. The article is based on several scientific methods, such as a historical and comparative approaches, a review of works and reports on the issue, and experience gained in our university courses. The article provides a brief political science excursion into the history of the instrumentalization of the ethnic factor as a source of political destabilization in time and space, before focusing on the cases of the Tuareg and Fulani ethnic groups in Mali, which reached the stage of political separatism and international terrorism. The practical value and theoretical necessity of this analysis is seen in the fact that the results of the work can be studied in the educational process at universities and in centers of political research, as well as in the process of negotiations and political decision-making. The author of the article comes to the conclusion that the problem of destabilization of Malian and other states in the Sahel (Burkina Faso and Niger) is associated with the expansive policy of Western powers, especially France, to obtain, preserve and strengthen their national, geopolitical and geostrategic interests in the region. The main instrument for the implementation of this policy is the creation and maintenance of ethno-separatist and terrorist groups.