Traditional phraseology research tends to start from the assumption that the geographical spread of idioms of one individual language is identical to the area where that individual language is spoken. This assumption, however, is not correct for all idioms. Especially with respect to German, one has to take into account that many idioms are known only within a limited area, e. g. because of their dialectal origins. Linguistic geographical studies on phraseology are usually restricted to aspects of the German pluricentricity. What has been overlooked is the fact that an independent phraseology was beginning to develop in the former GDR. Furthermore, the fact that idioms may exist in much larger areas than that of one individual language is largely unexplored. The aim of this paper is to point to problems of phraseology research in an areal framework. Two case studies on the distribution of idioms demonstrate that any research in areal phraseology must start with comprehensive empirical work.