It has its roots mainly in Old Polish[clarification needed] and also has strong influences from Czech and German and, to a lesser extent, from Vlach and Slovak.

[15] The language of Cieszyn Silesia was a result of a historical evolution, shaped by the territory's geographical location, affected by political affiliation and migrations of people.

The region was almost always peripheral—at the south-eastern edge of Silesia and the Diocese of Wrocław, in Poland under the Piast dynasty, and as a fee of the Kingdom of Bohemia—however it is located near the wide, northern opening of the Moravian Gate, on the most popular if not the shortest route from Prague or Vienna to Kraków, and from Wrocław to Upper Hungary (modern day Slovakia).

In a few decades after the establishment of the Duchy of Teschen, roughly at the same time it became a fee of the Kingdom of Bohemia (1327), written documents began to be produced in the local ducal chancellery.

Probably due to the peripheral location and a certain level of autonomy the cancellaria bohemica in the Duchy of Teschen was preserved after the Battle of White Mountain (1620), in contrast to the region of Bohemia.

They sometimes contained nasal vowels, one of the first traits differentiating early medieval Polish and Czech: they were present in the place names later inhabited by Cieszyn Silesian-speaking people, like Dambonczal (Dębowiec), but not in the area settled by Moravian-Lach population[note 5].

[17][18] From the 13th and consolidated in the 14th century was the spirantization g ≥ h, another major trait delineating from then on Polish and Czech, as well as Lach and Cieszyn Silesian dialects.

[17] In the late 15th century (Brenna) the Vlachs reached the Silesian Beskids, bringing the shepherds culture and vocabulary, although they were by that time linguistically mostly Polish.

A bill of a locksmith from Fryštát, who in 1589 tried to issue it in the most prestigious at that time official language, was so riddled with mistakes, that some researchers (Leon Derlich [pl], Robert Mrózek [pl], Zbigniew Greń) consider it to be written de facto in a local variety of Polish, thus the very first Polish document in the region.

The influence of Czech in Upper Silesia, to that date similar in scope to the Duchy of Teschen, quickly waned, replaced by the growing imposition of the German culture and language, especially after 1749.

For example, in 1874 Andrzej Cinciała [pl], a Polish deputy to the Imperial Council of Austria, proposed to open a Polish-speaking teachers' seminar in Teschen, as well as a Czech-speaking one in Troppau (Opava).

This was strongly opposed by Eduard Suess, who called the local language not Polish, but Wasserpolnisch, a Polish-Czech mixture, not used in books.

In his dissertation Wiadomości o języku polskim w Szląsku i o polskich Szlązakach Bandtkie [wrongly] placed the border of Polish along the Ostravice River.

This was a politically motivated decision, however, as the Nazi censors would have forbidden publication of any title that linked Slavic languages to the recently annexed Cieszyn region.

[34] The earliest linguistically scientific modern subdivision of the Silesian dialects in Poland dates to Stanisław Bąk (1974), inspired by early 19th century work by Jerzy Samuel Bandtkie.

However, several writers and poets wrote in the dialect, including Adolf Fierla, Paweł Kubisz,[40] Jerzy Rucki,[40] Władysław Młynek, Józef Ondrusz, Karol Piegza, Adam Wawrosz and Aniela Kupiec.