Granica mazowiecko-litewska między Wizną a Grodnem z 1358 r

ENThe document which makes the basis of the present article was issued in Grodno on August 14, 1358. The issuer was Kestutis, a Lithuanian duke, while the receiver was duke Siemovit III, who – as the Polish king Casimir the Great’s liege – ruled as the only duke in Mazovia. The document states that Kestutis made an agreement with Siemovit by virtue of which the border between the lands of Lithuania and Mazovia was established on the basis of what the representatives of both parties determined. In a 2000 edition of the document the publishers found the document forged. The examination of the original performed by experts in paleography showed that the document is authentic. The Kingdom of Poland concluded some kind of an agreement with the Grand Duchy of Lithuania in 1356, the result of which was a longer period of peace between those countries. This helped regulate the controversial matters on the border between Mazovia (Wizna area and Goniądz district) and Lithuania (Grodno territory). That frontier territory was covered with woods, where permanent settlements were situated only on the outskirts, close to the rivers Narew and Biebrza from the side of Mazovia, and close to the river Niemen from the side of Lithuania. A lack of settlement was due to frequent invasions in the 14th century by Lithuanians and the Teutonic Knights, which order had their own state in Prussia. The Polish population, Mazovians, entered the woods from the west, while the Ruthenians approached from the east but before the border was established, the frontier was no man’s land in the political sense.