Center versus periphery (方言周圏論 Hōgen-Shūken-Ron, lit. "Surrounding-zones dialect theory") is a linguistic theory put forward by Japanese folklorist Yanagita Kunio explaining the usage of certain words in a language used in some regions while not in others. The theory may also explain the existence of other cultural features, or lack thereof, in differing regions; though it was specifically created to address linguistic differences.