Von does not signify royalty - it usually signified aristocracy of some level or other. Records were not destroyed to protect families - there are as many records of as many families as any where else. Many records of all sorts were destroyed during WW2 mainly because they were in the path of bombs or were destroyed in the wake of the fighting as the Allies closed in on all sides. Prussia is not a "combination of Germany and Poland". The Kingdom of Prussia was a part (some would say the most important!) of the German Empire which came to an end in 1919. Therafter it was part of Germany until 1945. East Prussia was a Province of Prussia and covered a large area round the Eastern end of the Baltic, stretching (roughly) from Danzig to Lithuania, Russia and southwards into inter-war Poland. In 1945 all parts of Germany east of the Oder-Neisse rivers, which included East Prussia, were were ceded to present day Poland with the northern half of East Prussia being given to Russia. Maps of the old boundaries are easily available to pinpoint towns and lists giving both old and new names are also easy to find.