A number of conquest attempts were launched against Prussia by Poland, (ref External link William Pierson book), also
] Chronicon Polonor. Ongoing military attacks in order to subjugate Prussia. Labuda disputes this. 

Marija Gimbutas in her book: The Balts - describes the Prussian and Baltic territory reaching much further west, south, south-west, south-east than the later Prussia, when Poland came into existense and conquered much additional territory (claimed by Polish to have been a "uniting of Polish tribes"), however for centuries rejected and fought against by the ones involved.

Prussians are also recorded as Ulmerugi, Holmrugi (Island Rugians in the Vistula river area. That name still showed up on maps of area around Culm, Culmerland, Kulmerland territory which was surrounded by the Vistula river.  

Boleslaw I claimed to have conquered (part of) the Prussians and even his headstone is supposed to have shown something like this. He also claimed to have put 'columns' (pillars) up in the newly conquered Prussian territory, to mark the new border of territory, which he now claimed as his, which was not his.

So ,Szopen, Culmerland was not Polish land- it was Prussian land, partially conquered temporarily by Poland. 

Gethen, Getae is yet another name for the Prussians, that name was still known to Polish historians as well.

Szopen's mentioning of Bruno of Querfurt as having taken part in Boleslaw I battles against Prussians 1015 also makes no sense, because Bruno was dead since 1009.