The sources for studying the demographic situation in the Romanian area, especially those from Moldova Principality and neighboring territories, increase quantitatively with the expansion of Russia towards South-Eastern Europe. During the Russo-Turkish War of 1806-1812, as well as during the conflagrations of the late XVIIIth century, the Russian Empire preferred to establish its own administration of occupation, which for the most efficient record of resources was used not only by its own apparatus, but also by the local administrative and ecclesiastical institutions of the Romanian Principalities, introducing several statistical tools for population records. Among the statistical instruments introduced during this period (e.g. forms, registers, etc.) that followed the record of the population at all stages of life, through civil status registers, in which births, marriages and deaths were recorded; confession registers of Orthodox believers; the forms of the churches and the service records of the clergy, where, in addition to the information about the status of the churches and the situation of the parish clergy, there was also information about the number of the population according to ethnic and gender composition, the latter are the object of our intervention. In the framework of this study, a series of information was exposed about the process of introducing Church Forms and clergy service statuses, a process initiated in December 1809, as a result of insufficient data presented by diocesan bishops and other church structures during the same year. Taking into account the value of the information contained in these sources, here we focused on the selection and accounting of the data regarding the numerical situation of the Christian-Orthodox population in the Pruto-Nistrian area in 1812. As a result of comparing the fiscal data contained in the Evideces of the Moldovan Treasury from 1808 and other statistical data known from the era with those contained in the Forms, we find that the data from the sources we considered, although they were used to clarify some information regarding the history of the Orthodox Church in Bessarabia. However, they were not used at their fair value to clarify those contradictions that continue to hover over the issue of the numerical composition of the population in the region newly annexed to Russia in 1812. Thus, following the analysis of the statistical data provided by several registers with the Forms that have reached us, it can be concluded that the population of the region not only approached the number of 300,000 people, but even exceeded it. Therefore, it would be recommended that researchers concerned with the study of demographic issues in the region not only refer to the records of a fiscal nature, which, although they are recognized to be of particular value. Nevertheless the information provided by the Forms allows verification of the veracity/correctness of the premiums, detailing some aspects, such as the ratio between churched and non-churched localities, the ratio between the male and female population, as well as other indicators that tax statistics from the early XIXth century do not record.