One thing you need to remember is that at that time there was no Poland. It was divided up between the three great empires, German, Russian and Austro-Hungarian. Your ancestors could well have been Polish, speaking Polish but would also speak German because that was the official language and they lived in the part of Poland which was under German jurisdiction. Poles, Ukrainians, Czechs, Slovenes, Croats (and a few others) in the A-H Empire would say they were Polish or whatever, speak Polish or whatever but would say they were, or be described as, "Austrian" on official documents which would be in German because that was also the official language. From what you are saying it would seem to point to "German" Poland. It would be an idea to google up a map of the German Empire and it will be clearer, but I think you really need at least the name of an area to make progress - naturalisation documents should tell you that.