[Genealogy.net-users-en] Germans in Posen

I am looking for information on why, when and from where Germans moved into the Posen area. My Zabel family came from around Schneidemuhl (now Pila). The always called themselves German.

I have heard about their expulsion from Poland (because they were not Catholic) but have not found anything to help me understand why they were there in the first place.

Wilhelm Zabel born Schneidemuhl (Pila) 1842, immigrated to USA 1905; Frederick Zabel born Wissik (Wysoka) 1877, immigrated 1894.

I was told many years ago that the records of Germans in Poland had been moved to Germany. Did this refer to civil and/or church records? A brief history of Germans who emigrated to Posen would be most appreciated as I don't know where to search.

I would greatly appreciate any help or suggestions .
Carol Zabel