So whenever I look into this, all I find is a bunch of questions about why Russia is so underpopulated, relative to the massive size of their country. This seems obvious: most of Russia is freezing cold Siberian land. It makes sense that an east so vast and hostile wouldn’t be densely populated.
However, taking this into consideration, it’s actually more surprising to me just how heavily populated this country as a whole is. Sure, the east is pretty vast and relatively empty, but Russia’s total population is still the 9th largest on earth. This is for a country that is far north in Europe with no real natural barriers to protect them from neighbouring countries. On top of this, the country has a pretty harsh climate besides their land in the south, though most of the population seems concentrated more north.
So how is this the case? Why is it that Russia - remote, unprotected, with an overwhelmingly harsher climate than most of Europe - has such a gigantic population?
As you already stated yourself: Russia isn't actually densely populated. With a population density of 8,4 people per square kilometer it's in fact very sparsely populated. Compared to other European countries like for example Germany (232), the Netherlands (417) or the UK (274) Russia seems almost empty.
Now we have to look where the 144 million inhabitants of Russia are concentrated. For this we can have a look at this graphic:
As we can easily see the majority of Russia's population is located in south-western regions of the country.
Now are those regions really so "far up north" and "freezing cold" as you seem to imagine?
Even Moscow which is higher in the north than most of the dense populated regions is "only" at 55° north. That's on the same latitude as cities like Edinburgh or Copenhagen, only a bit farther north than Manchester or Hamburg and significantly farther south than Scandinavian capitals like Oslo, Helsinki and Stockholm. Certainly: The continental climate of Russia is harsher in the winter than it is in cities more to the west. But it's not the north pole.
If we look at the other hand at the densely populated areas close to the black sea, we recognize that they are actually on the same latitude as cities in southern European countries. Krasnodar for example has a climate chart that is quite similar to what you find in northern Italy. Significantly warmer than Berlin, for example.
So we can conclude that the parts of Russia that are densely populated are mostly not so very much different from the rest of Europe.
Besides this: Having a harsher climate than other regions isn't only bad and it's by far not the only factor that makes a region habitable.
The "black soil" that is found in southern (mostly south-western) Russia (and Ukraine) is very good for agriculture. When it comes to goodconditions for grain production that's the region you want to look at. More fertile than almost anywhere else in Europe.
I addition to what I already stated we also have to consider that soviet politics aimed for an urbanization and centralization. This means that many Russian cities are more heavily populated than they'd be if only climate, agricultural fertility etc. were the deciding factors. So if it wasn't for the influence of the government, the population of Russia probably would be even more concentrated in the fertile and milder regions and not so much in the urban centers.
