The paper deals with the history of agrarian development of the East European plain in the frame of the geoenvironment concept of agricultural landscapes, taking Kargopol’ region as an example. A large agricultural landscape unique for the middle taiga zone was formed there no later than in the twelve century. We have analyzed the natural environment of the Kargopol’ region and its influence on the agrarian development and the rural settlement pattern. We paid particular attention to the karst, which was widespread in the area and its relation with agricultural landscapes. We made mathematical modelling of both elementary agricultural landscape spatial pattern and the corresponding rural settlement pattern. A feature of the proposed modeling is its emphasis on the relationship between the natural landscape and agricultural landscape. The mathematical morphology of landscape (method proposed by A. Victorov) and, in particular, the karst system model is the base of modeling. This model is first used for the analysis of cultural (anthropogenic) rather than natural landscapes.