Lithuania proper (; ) refers to a region that existed within the Grand Duchy of Lithuania 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. The Lithuania Proper (Lithuania Propria) was always distinguished from the Ruthenian lands since the Lithuanians differed from the Ruthenians in their language and faith (Paganism in the beginning and Catholicism since 1387). The term in Latin was widely used during the Middle Ages and can be found in numerous historical maps until World War I. Lithuania proper sometimes is also called Lithuania Major, particularly in contrast with Lithuania Minor. The Lithuanian geographer Kazys Pakštas wrote that Lithuania proper was known since the administrative division of the Grand Duchy of Lithuania in 1566, when the name was assigned to the palatinates of Vilnius and Trakai. The name was used in documents and maps. Lithuania proper also included the Duchy of Samogitia. Evolution of the term Before the Grand Duchy of Lithuania 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 Ašmena area, ethnic Lithuanian lands in modern Belarus. According to Mikola Yermalovich (although his reliability is questioned by other scholars) Lithuania (, literary: Lithuania of chronicles) was in the upper Nemunas region, now in modern Belarus. In the Grand Duchy of Lithuania Scholars often use term Lithuania proper to refer to lands inhabited by ethnic Lithuanians as opposed to lands controlled by the Grand Duchy of Lithuania inhabited by Ruthenians (ancestors of modern Belarusians, Ukrainians and Russians), Poles, Lithuanian Jews or many other nationalities. Already during the Grand Duchy times, Lithuania Proper was a term designated to land where Lithuanians live. Administratively it consisted of Vilnius Voivodeship, Trakai Voivodeship and the Duchy of Samogitia. This division continued even after Polish-Lithuanian Commonwealth was partitioned. Thus Grand Duchy of Lithuania was divided into such historical regions: Samogitia (literally Lower