German invasion had occurred. Background The German invasion and the war was the factor changing the former order of the Baltic area. While German Order was expanding its territory, the holding of Lithuanian grand dukes was withdrawn in some places. The political situation during the war was influenced by the following factors: The situation of the war technologies. The Teutonic Order built many stone fortresses in the Baltic lands thus gaining the control over the ethnically foreign lands. Nadruvia was full of German castles. The geographical situation. The Neman became a kind of a front line between the Order and Lithuania during the several decades of the war after the German invasion. There were German castles up to Kaunas by Neman in the 14th century. Germans built their castles by the Lithuanian and vice versa. The wide forest stretched in the land by the left side of the middle reaches of the Neman, what was Sudovia or Suvalkija. It could originate as a wide border between Lithuanian and Sudovian tribes before pre-nation times of Lithuanians and also could expand due to the war. The land was sparse of German castles. The conquered Baltic lands were all called Prussia by the Teutonic Order but not all the lands with the German castles managed to build in them became occupied. The presence of the Neman river, also possibly the forests in Sudovia, Karšuva afforded the most economical variant for the defensive fortifications. The war probably changed the situation of populations of the area: The demographic situation. The population of the territory which lain between the chief lands of Lithuanian state and Nadruvia – what was in the Grand Duchy of Lithuania and the northern half of Sudovia or Suvalkija – was sparse. Nadruvia possibly also became more depopulated than those Lithuanian lands which lay on the right side of the Neman during the war between the Teutonic Order, the Old Prussians, and the Grand Duchy of Lithuania. The ethnical situation. The German invasion and the war between the latter state and Lithuanian one reduced, was expelling the local population to some extent and impelled some migrations of Baltic tribes. In the abstract, Nadruvia, Scalovia and Sudovia had to be inhabited by Nadruvians, Scalovians and Sudovians. All these three tribes are considered to have once been western Baltic, but the Lithuanian impact, close relations and immigration, is likely to be occurred before the