A dialect continuum is a range of
dialects spoken across a large geographical area, differing only slightly between areas that are geographically close, and gradually decreasing in
mutual intelligibility as the distances become greater. Dialects separated by great geographical distances may not be mutually comprehensible. According to the
Ausbausprache - Abstandsprache - Dachsprache paradigm, these dialects can be considered Abstandsprachen (i.e., as stand-alone languages). However, they can be seen as dialects of a single language, provided that a common
standard language, through which communication is possible, exists.
See more at Wikipedia.org...