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.

In year 1612, cartographer Eilhard Lubinus – while working on his map of Pomerania – travelled from the direction of Pollnow towards Treblin on his way to Danzig.

While staying in the manor house of Stanislaus Stenzel von Puttkamer in Treblin, he noted in his diary: "we have entered Slavic-inhabited lands, which has surprised us a lot."

Later, while returning from Danzig to Stettin, Lubinus slept over in Wielka Wieś near Stolp, and noted: "in the whole village, we cannot find even one German-speaker" (which caused communication problems).

He noted that villages owned by Otto Christoph von Podewils – such as Dochow, Zipkow and Warbelin – were inhabited entirely by Slavic-speakers.

He also noted that local priests and nobles were making great efforts to weed out Slavic language and turn their subjects into Germans.

[28]: 31 Karl Andree, Polen: in geographischer, geschichtlicher und culturhistorischer Hinsicht (Leipzig 1831), gives the total population of West Prussia as 700,000 – including 50% Poles (350,000), 47% Germans (330,000) and 3% Jews (20,000).

[29] Modern estimates of Kashubian population in West Prussia in the early 19th century, by county, are given by Leszek Belzyt and Jan Mordawski: According to Georg Hassel, there were 65,000 Slavic-speakers in the whole Provinz Pommern in 1817–1819.

Modern estimates for just eastern parts of Pommern (Western Kashubia) in early 1800s range between 40,000 (Leszek Belzyt) and 25,000 (Jan Mordawski, Zygmunt Szultka).

The bulk of Slavic population in 19th century Pommern was concentrated in its easternmost counties: especially Bytów (Bütow), Lębork (Lauenburg) and Słupsk (Stolp).

Kashubs descend from the Slavic Pomeranian tribes, who had settled between the Oder and Vistula Rivers after the Migration Period, and were at various times Polish and Danish vassals.

[8] On the other hand, Pomerelia since the Middle Ages was assigned to the Kuyavian Diocese of Leslau and thus retained Polish as the church language.

Only the Slovincians in 1534 adopted Lutheranism after the Protestant Reformation had reached the Duchy of Pomerania,[35][36][37] while the Kashubes in Pomerelia remained Roman Catholic.

Although his efforts did not appeal to locals at the time, Kaszubian activists in the present day have claimed that Ceynowa awakened Kashubian self-identity, thereby opposing both Germanisation and Prussian authority, and Polish nobility and clergy.

[39] He believed in a separate Kashubian identity and strove for a Russian-led pan-Slavic federacy,[39] He considered Poles "born brothers".

[40] Ceynowa was a radical who attempted to take the Prussian garrison in Preussisch Stargard (Starogard Gdański) during 1846 (see Greater Poland uprising),[41] but the operation failed when his 100 combatants, armed only with scythes, decided to abandon the site before the attack was carried out.

[40][43][44][45][46] Between 1855 and 1900, about 100,000 Kashubs emigrated to the United States, Canada, Brazil, New Zealand, and Australia in the so-called Kashubian diaspora, largely for economic reasons.

[40] While resenting the disrespect shown by some Prussian officials and Junkers, Kashubians lived in peaceful coexistence with the local German population until World War II, although during the interbellum, the Kashubian ties to Poland were either overemphasized or neglected by Polish and German authors, respectively, in arguments regarding the Polish Corridor.

[49] As a result of political mistrust and coercion to declare Polish identity many Kashubians turned away from Poland and chose opting for Germany.

[58] Given the past nationalist interests of Germans and Poles in Kashubia, Barbour and Carmichel state: "As is always the case with the division of a dialect continuum into separate languages, there is scope here for manipulation.

[60] Krofey, pastor in Bütow (Bytow), published a religious song book in 1586, written in Polish but also containing some Kashubian words.

[60] Brüggemann, pastor in Schmolsin, published a Polish translation of some works of Martin Luther (catechism) and biblical texts, also containing Kashubian elements.

[60] Scientific interest in the Kashubian language was sparked by Christoph Mrongovius (publications in 1823, 1828), Florian Ceynowa and the Russian linguist Aleksander Hilferding (1859, 1862), later followed by Leon Biskupski (1883, 1891), Gotthelf Bronisch (1896, 1898), Jooseppi Julius Mikkola (1897), Kazimierz Nitsch (1903).

The Young Kashubian movement followed, led by author Aleksander Majkowski, who wrote for the paper Zrzësz Kaszëbskô as part of the "Zrzëszincë" group.

They were blessed by priests on Palm Sunday, following which parishioners whipped each other with the pussy willow branches, saying Wierzba bije, jô nie bijã.

The pussy willows, blessed by priests, were treated as sacred charms that could prevent lightning strikes, protect animals, and encourage honey production.

Pope John Paul II visited in June 1987 and appealed to the Kashubes to preserve their traditional values including their language.

[62][63] In 2005, Kashubian was for the first time made an official subject on the Polish matura exam (roughly equivalent to the English A-Level and French Baccalaureat).

Old Kashubian culture has partially survived in architecture and folk crafts such as pottery, plaiting, embroidery, amber-working, sculpturing and glasspainting.

[68] When it comes to mitochondrial DNA haplogroups, according to a January 2013 study, the most common major mtDNA lineages among the Kashubians, each carried by at least 2.5% of their population, include J1 (12.3%), H1 (11.8%), H* (8.9%), T* (5.9%), T2 (5.4%), U5a (5.4%), U5b (5.4%), U4a (3.9%), H10 (3.9%), H11 (3.0%), H4 (3.0%), K (3.0%), V (3.0%), H2a (2.5%) and W (2.5%).