In the present paper the authors compared skeletal populations (2421 individuals) excavated from four cemeteries, namely Hajdúdorog-Gyúlás (10th century AD), Hajdidorog-Temetöhegy (11th century AD), Hajdúdorog-Katidülö (12th-13th century AD) and Hajdúdorog-Szálldáföld (12th-13th century AD) from a micro-region of Northern Hajdúság (located in the northern part of the Great Hungarian Plain in Hungary in the Carpathian Basin) based on demographic data. The cemeteries were dated to the age of the Hungarian conquest and the Arpadian age and provided representative data for anthropological research. Previous studies based on craniological and archaeological investigations have already suggested that there was discontinuity in the population history between the 10th and the 11th centuries AD and continuity between the 11th and 12th centuries AD in this region. This hypothesis could be partially supported by demographic investigations because conclusive evidence was found that there must have been a change in the population at the turn of the 10th and 11th centuries AD, and there was certain continuity between the 11th and 12-13th centuries AD. The authors suppose that there were two crises in the examined period: the first crisis set in at the transition from the pagan era (10th century AD) to the Christian era (from the beginning of the 11th century AD, with population resettlements within the Carpathian Basin), the second might have been more moderate and meant burying the dead of the populations lacking a church in the churchyards of villages which had a church. At that time one graveyard around a church may have been used by several village populations.