Editing Japanese dialects (section)

=== Theory of Peripheral Distribution of Dialectal Forms ===
West geographically separated areas seem to have been influenced by Eastern traits. The phonology of Tokyo has influenced Western areas like San-in, Shikoku and Kyushu. Eastern morpho-syntactic and lexical characteristics are also found in the West. These instances cannot be explained as borrowing from the Kyoto speech as Tokyo did because between the regions Eastern traits are not contiguous and there is no evidence that regions had contact with Tokyo. One theory argues that the Eastern type speech was spread all over Japan at the beginning and later Western characteristics developed. The eastward spread was prevented through the geography of Japan that divides East and West that separated the cultures in each of them socio-culturally until this day.<ref name=":2" />

[[Kunio Yanagita]] began his discussion for this theory in analysing the local variants for the word "snail". He discovered that the newest words for snail are used in the proximity of Kyoto, the old cultural center, and older forms are found in outer areas. Since the spreading of newer forms of words is slow, older forms are observable in the areas farthest away from the center, creating in effect a situation in which older forms are surrounded by newer forms. His theory in the case of Japan argues that the spread of newer forms happens in a circular pattern with its center being the cultural center. However, this theory can only be true if the characteristics located in peripheral areas are reflections of the historical ones.<ref>Shibatani (2008: 202) </ref>