Central Asia has been a zone of contact between Asian and European travellers since the beginning of the XXth century for anthropologist and as far back as the middle ages for travellers. With new archaeological data and extended collaborations between European, Siberian and Chinese researchers, the area of contact is now thought to have been much larger, encompassing the entire zone of Central Asia, south Siberia and the peri-Baikal area. Nowadays, it seems, in fact, that central Asia was only an extension of an initial zone delimited by what we call the Altaï/Baïkal spatial complex, originally a natural border and a zone of admixture between people from Asia in the south, and from Siberia in the north. Understanding the peopling of this spatial complex in relation to adjacent areas is of special interest for the study of European, Asian and American populations. In this paper, we discuss the maternal population history of this spatial complex by re-analyzing mt DNA data from modern populations at the haplogroup frequencies level and rather than the molecular level. This approach allows to apply original statistical analyses that offer a global view of the processes that shaped the population differentiation in Siberia.