Lithuania proper (Latin: Lithuania propria; Lithuanian: Didžioji Lietuva, literally: "Genuine Lithuania"; Yiddish: ליטע, Lite) refers to a region which existed within the Grand Duchy of Lithuania, and where the Lithuanian language was spoken. The primary meaning is identical to the Duchy of Lithuania, a land around which the Grand Duchy of Lithuania evolved. The territory can be traced by Catholic Christian parishes established in pagan Baltic lands of the Grand Duchy of Lithuania subsequent to the Christianization of Lithuania in 1387. They were quite distinguishable, since Ruthenian parts of the Duchy have been already baptised in an orthodox manner. The term in Latin was widely used during the Middle Ages and can be found in numerous historical [1] maps until World War I.
Lithuania proper sometimes is also called Lithuania Major (Lithuanian: Didžioji Lietuva), particularly in contrast with Lithuania Minor.
Historians designate Lithuania Proper (or Land of Lithuania in a narrow sense) as a Lithuanian land that existed prior to Grand Duchy of Lithuania, near other lands: Land of Nalšia, Land of Deltuva, Land of Upytė. According to Henryk Łowmiański Lithuania Proper was in nucleus of future Trakai Voivodeship between rivers: Nemunas, Neris and Merkys. Tomas Baranauskas suggests that Lithuania Proper was around Ashmyany area, then ethnic Lithuanian lands now in Belarus. According to Mikola Yermalovich (although his reliability is questioned by other scholars) Lithuania (Belarusian: Летапiсная Лiтва, literary: Lithuania of chronicles) was in the upper Neman region, now in modern Belarus.