The post you are reporting:
No, Howard! originally Prussia was a Slavic area with a name similar to Prussia (from where the name comes from), but these Slavs were not Poles. Poland was a lot smaller. Many of these Prussian Slavs integrated with the Germans who settled there.
Similarly, there were various Slavic peoples in nowadays eastern Germany, many of them were actually Serbs, that is, Black Serbs, and they also had other names according to their particular tribe or district. Many of these also integrated with the Germans, but today there are Serbs living in south eastern Germany whose forbears kept to their identity, thus they speak their Slavic Serbian language, which is similar to Serbian spoken in Serbia and to other Slavic languages. They are called in Germna both: Sorben and Wenden, two names indicating the same people.
The White Serbs moved to the Balcans in the seventh century, as did the Croats and the Slovenians, the Macedonians and the Bulgarians.
Many names of eastern German cities and towns are in fact of Slalvic origin, coming from these Black Serbs, for example: Chemnitz.
The Poles are also Slavs, but the Slalvic Prussians were a separate people.
As for White and Black indicateing Slavic peoples, these terms were used often in the past and were synonim for East and West, in a certain sense, as it indicated two separate groups of the same Slavic people who lived in different areas.
Hence there is a White Russia.