I have my doubts about the accuracy of this map. According to it, a huge chunk of central Russia is 'peopled' - yet there are many parts of it where you can try to bushwack through the taiga for two weeks, without ever running into a soul.

I assume that the 'regions' that were painted in the map are oblasts (Russian equivalents to counties) - so if there's a giant oblast, with a medium-sized town at its center, but few people living in the outskirts, the entire region gets painted orange.