As for dialects, due to the geographical constraints of the Japanese archipelago, which stretches east to west (consisting mainly of Honshu, Kyushu, Shikoku and nearby islands), there were enough differences that those who lived in the east and the west had difficulty communicating before modern times, though the differences were only in phonemes and vocabulary; there was not much difference grammatically.
方言差については、東西に長い日本列島（主に本州・九州・四国と周辺離島）の地理的制約もあって、近代以前は東西に離れた者どうしでは意思疎通に困難を来すほどの差異があったが、音韻や語彙を中心とした相違にとどまり、特に文法面では大きな差はない。