[keiferski]

Most of these areas were only “a part of the Russian empire” because Russia had previously invaded them. You seem to have completely forgotten the Partitions of Poland, the numerous uprisings in the 19th Century, and the defeat of the Soviet Army by Poland following WWI, which thus curtailed Soviet expansion. Clearly the Poles did not want to be a part of the Russian empire. The same story is essentially true to a varying degree for most other cultures in the area.