I would argue that the main topic of the story is the effect that political events, especially the redrawing of national boundaries, has on individuals and their families. In The Endless Steppe the Rudomins have been forcibly uprooted from their home in Poland as part of the infamous Nazi–Soviet Pact between Hitler and Stalin. They are then forced to endure a long, hard, and brutal journey to the inhospitable steppes of Siberia.
As part of the notorious secret protocols of the pact, Poland was carved up between the two dictators along with Romania, Finland, and the Baltic states. The Endless Steppe shows us the often harrowing human stories behind such momentous historical events. Specifically, it reminds us of how ordinary civilians invariably find themselves caught up in terrifying situations not of their own making. Even in so-called peacetime the lives of innocent people can be utterly ruined by the actions of those who govern them. Without any help or support from the authorities, such people need to dig deep and somehow find the strength and courage to carry on. And that's precisely what the Rudomins must do in The Endless Steppe.