Few European countries have gone through as much as Poland during the twentieth century. Even among the countries of Central and Eastern Europe, which during the ‘Age of Extremes’ experienced the substantial losses and movement of tens of millions of people, Poland's history is somewhat unique, as most of these expulsions affected the Polish border regions. Although not the only culprit, one can make a strong case that the border changes were a primary factor, having – for better or worse – a strong effect on the economy, the society and the general development of Poland. Poland has, nevertheless, been economically successful since the 1990s. It is thus with good reason that two questions have played a major role in the historiography of economic and social trends in twentieth-century Poland. The first one was whether the ‘border changes’ were a burden, or if Poland was able to profit from them. The second question asks whether Poland was able to modernise because of them. At the same time, few authors recognised that both issues are closely intertwined. Emphasising their interconnection is the main purpose of this review.