[en] In the Middle Ages, frontier regions could had a special status of double jurisdiction. An example of this is the land near the Lithuanian-Novgorodian border called in Polish-Lithuanian historical texts “Chernokunstvo”. The Grand Dukes of Lithuania, and then the Kings of Poland received from them monetary and natural tribute. The remaining part of the tax was collected by the Novgorodian administration. The main questions as to the phenomenon of “Chernokunstvo” are related to the time and the cause of the formation of a joint jurisdiction, as well to the as economic situation, and the administrative systems. Most probably, the system of double administration could be linked to the Lithuanian-Novgorod compromise in the 14th–15th centuries. To clarify this problem, it is necessary to apply a new approach to the medieval texts as well as to archaeological materials.