Immigrants have been making their way to Europe for tens of thousands of years. The first modern humans the first real immigrants came north from Africa through the Middle East. Since then, periodic waves of migrants have helped redefine Europe's population, its food, its knowledge. After World War II, most migrants headed to northern Europe but as the south has prospered over the past 20 years, it has drawn in growing numbers of people looking for a better life. By the mid-2000s, migrants headed for southern Europe accounted for more than 60% of the continent's new arrivals. They swung the hammers during Spain's construction boom, changed diapers in Greece and worked Italy's fields.
European immigration policy has become more bureaucratic over the years. In the south, where enforcement of rules has been more lax and informal economies are large, working illegally is often easier than getting proper permits.
The economic crisis will slow the flow but is unlikely to undo the demographic shift, not least because the birthrate among immigrants is much higher than the general population's. "If there's a lesson that can be learned from the northern European experience, it's that temporary migrants tend to remain," says Joaquín Arango, professor of sociology at the Complutense University of Madrid. Here's another: when a society marginalizes its newest members, trouble ensues. Southern Europe needed its immigrants. Now it needs to find a place for them. TIME takes a look at three countries just beginning to grapple with that fact.