In the 1970's the Germans started importing Gastarbeiter (guest workers), mostly from Turkey. Turks were the butt of jokes, sort of like Pollack jokes in the United States. They were seen as sort of hapless, and they were not considered permanent residents, merely guests, who were expected to return to their home countries. Eventually, they brought their families along, their kids went to school in Germany and felt that they were Germans.
All you have to do is look at the current version of die Mannschaft, the German national soccer team.