Sejny 'seIny (Seinai) is a town in north-eastern Poland and the capital of Sejny County, in Podlaskie Voivodeship, close to the northern border with Lithuania and Belarus. It is located in the eastern part of the Suwałki Lake Area (Pojezierze Suwalskie), on the Marycha river (Seina in Lithuanian for which the town was named), being a tributary of the Czarna Hańcza. As of 1999 it had almost 6,500 permanent inhabitants, with a strong seasonal increase during the tourist season. According to a legend, the town of Sejny was started by three of the old knights of King of Poland Władysław II Jagiełło, who after the Battle of Grunwald granted them a land parcel in what is now Sejny. The three were very old and named the settlement Seni, which is a Lithuanian word for Old Men. The name was purportedly given to the city of Sejny. However, no archaeological findings or documents support this legend. The name is Yotvingian in origin. The linguist Jerzy Nalepa has proposed that the nearby river name Sejna (now Marycha) and the city name are Yotvingian. This conclusion is based on two features: the presence of West Baltic "s" (vs. modern Lith. "š") retention of the diphthong "ei". Cognates include Pol. siano and Lith. šienas, both meaning "hay". In the early Middle Ages the area comprising modern Sejny was inhabited by the Yotvingians, one of the Baltic tribes closely related to Lithuanians that had arrived in the area in the first millennium. There was ongoing strife for the area since the 13th century between the Teutonic Order and Lithuania. This resulted in the area being almost completely depopulated, with only a few of the indigenous Yotvingians surviving. The first written record of the area where the town now lies dates to 1385, noting an armed raid of the German knights from Castrum Leicze (Giżycko) to Merkinė. After the Treaty of Melno in 1422, Teutonic-Lithuanian border was determined, people began to return to the forests in the area.