Emerged from the preoccupations to research the process of population evolution in historical Moldavia, the present study proposes an analysis of the spatial distribution and geographic relevance of the hydronyms in this region. For this purpose, 2040 watercourses, identified in various cartographic sources, were inventoried. They were given additional information on the origin of their names and meanings. The paper uses the etymological explanations taken from the consulted bibliography and the categories of geographical relevance related to the elements of the natural or anthropic framework. Beyond the limits imposed by the inherent documentary gaps or controversies in explaining the etymology and the meaning of some names, the results obtained by analysing the statistical distribution of the retained categories represented the support of some typological classifications at the level of the 32 main hydrographic basins. The conclusions drawn show the existence of strong connections with the spread of some (present or past) ethnic groups, as well as with the features of the natural environment or induced by specific socio-economic relations.