Assimilation proceeds the faster the closer are the contacts of the minority with the majority and the weaker the contacts within the minority itself and the weaker its contacts with fellow nationals living at a distance. From that it immediately follows that the social positions of the different nationalities must be of special significance in this regard, for personal contacts are more or less bound up with class membership. Thus, particular social strata in an environment of a foreign nation can not only maintain their own customs and own languages for centuries but also assimilate others to them. However, the Ruthenian peasant in Eastern Galicia who by upward social mobility joined the ruling class also became a Pole, and the Czech peasant's son who rose into the bourgeoisie became a German. In a society organized by classes or castes, different nations can live side by side in the same territory for centuries without losing their national distinctness.
History provides enough examples of that.
Another example is the Gypsies. If social contacts between the nations are lacking, if between them no connubium and only to a restricted extent commercium exists, if changing one's class or caste is possible only in rare exceptional cases, then the conditions for national assimilation are rarely present. Thus, self-contained peasant settlements inside a country inhabited by a population with another language could maintain themselves as long as the agricultural strata were bound to the soil. As, however, the liberal economic order set aside all bonds, removed the special privileges of classes, and gave the workers freedom of movement, the rigid national stratification was loosened. Upward social mobility and migrations made national minorities disappear rapidly, or at least pushed them into defensive positions tenable only with difficulty.