Historical population thumb|Kashubian population in year 1892 Until the end of the 12th century, the vast majority of inhabitants of Pomerania (Hither, Farther and Eastern) were Slavic-speakers, but the province was quite sparsely populated, with large areas covered by forests and waste lands. During the 13th century, the German began in this region. Slavic dukes of Pomerania such as Barnim I (1220–1278) – despite calling themselves – contributed a lot to the change of ethnic structure by promoting German immigration and granting land to German nobles, monks and clergy. The Slavic ruling dynasty itself started intermarrying with German princesses and became culturally Germanized over time. Wendish commoners became alienated in their own land, their culture replaced by that of newcomers. All of this led to Germanization of most of Slavic Pomeranians and the gradual death of their Slavic language, with the general direction of assimilation and language shift from west to east.thumb|upright=1.4|Mother Tongues of West Prussia, according to the 1910 Census; Kashubians are indicated in shades of blue, in northern West PrussiaJohannes Bugenhagen wrote that at the beginning of the 16th century the German-Slavic language border was near Koszalin. During the 17th century, the border between areas with mostly German-speaking and mostly Slavic-speaking populations ran more or less along the present-day border between West Pomeranian and Pomeranian Voivodeships.
Historical population thumb|Kashubian population in year 1892 Until the end of the 12th century the vast majority of inhabitants of Pomerania (Hither Farther and Eastern) were Slavic-speakers but the province was quite sparsely populated with large areas covered by forests and waste lands During the 13th century the German began in this region Slavic dukes of Pomerania such as Barnim I (1220–1278) – despite calling themselves – contributed a lot to the change of ethnic structure by promoting German immigration and granting land to German nobles monks and clergy The Slavic ruling dynasty itself started intermarrying with German princesses and became culturally Germanized over time Wendish commoners became alienated in their own land their culture replaced by that of newcomers All of this led to Germanization of most of Slavic Pomeranians and the gradual death of their Slavic language with the general direction of assimilation and language shift from west to eastthumb|upright=14|Mother Tongues of West Prussia according to the 1910 Census; Kashubians are indicated in shades of blue in northern West PrussiaJohannes Bugenhagen wrote that at the beginning of the 16th century the German-Slavic language border was near Koszalin During the 17th century the border between areas with mostly German-speaking and mostly Slavic-speaking populations ran more or less along the present-day border between West Pomeranian and Pomeranian Voivodeships