The theory of it originating from Pskov (Pleskov), Russia has been disproved due to the fact that Joseph and his family originated from the Tetiiv area in what is today called Ukraine. One theory that has some credibility is the town of Plyskiv, Ukraine, which it may be a corruption of. It is important to note that there are others from Eastern Europe who share a similar name, such as General Grigorii Plaskov, but there is no known relation. However, this is not to say that any relation is impossible.
