There exists an interesting link between the people of ancient Japan and the people of Wu, a historic region in southern China. Wu was also one of the Three Kingdoms which controlled the same region. The character 'wu' (呉) is pronounced 'go' in Japanese.
A map of the Three Kingdoms, courtesy of Wikipedia
Records by Chinese emissaries to Japan from the Wei and Jin dynasties describe the contemporary Japanese as having customs similar to the people of the Wu kingdom. Furthermore, the Japanese referred to themselves as descendants of the Wu. Many words in modern Japanese have pronunciation similar to Wu words of the same meaning, reflecting an ancient tie with the Wu.
As an anecdote, I have found that people from Shanghai pick up Japanese quicker than those from northern China.
Traditional Japanese dress, popularly referred to as kimono, traces its roots to Wu-style dress. In fact, the proper word for "traditional Japanese dress" is gofuku (呉服), lit. "dress of Wu".
(As a side note, Manchu-style dress is often mistaken for traditional Chinese dress. The actual style of clothes the ancient Chinese wore was similar to kimono and the Korean hanbok. The Manchu subdued China circa 1640 and forced the Han Chinese populace to abide by their customs, including adopting Manchu-style dress and a pigtail hairstyle.)
Did you know...? =)