Transylvanian’s documents from the seventeenth century, are many and varied. They refer to Transylvania, Moldova, and Wallachia. The narrative sources describing the impact of political factors and natural disasters on the demographic development of the three countries. The reconstruction of the numerical evolution of the population is possible only for Transylvania. Here they had numerous population registers (registers of the serfs (urbaria), parish registers, military registers, etc.). Date from Transylvanian shows that in this geographical region, as in the rest of Europe, in the seventeenth century the population growth was hampered by the historical context.