Wenzhounese (simplified Chinese: 温州话; traditional Chinese: 溫州話; pinyin: wēnzhōuhuà), also known as Oujiang (simplified Chinese: 瓯江话; traditional Chinese: 甌江話; pinyin: ōujiānghuà) or Dong'ou (東甌), is the speech of Wenzhou, the southern prefecture of Zhejiang Province, China. It is the most divergent division of Wu Chinese, and is sometimes considered a separate language. It features noticeable elements of Min, which borders it to the south. Oujiang is sometimes used as the broad umbrella term, reserving Wenzhou for Wenzhounese proper in sensu stricto. Wenzhou is not mutually intelligible with other varieties of Wu neighboring it to the north and west, let alone with Min Dong to the south or with the official language of China, Mandarin. Due to its remarkably long history and the geographical features (isolation) of the region on which it is located, Wenzhou Chinese is so eccentric in its phonology that it has the reputation of being the "least comprehensible dialect" for an average Mandarin speaker. It preserves a large amount of vocabulary of classical Chinese lost elsewhere, earning itself the commonly-known name "the living fossil", and has distinct grammatical differences from Mandarin . It is commonly considered as the hardest dialect of China due to its remarkably long history, eccentricity and unique grammar structure Wenzhounese is one of five Sinitic varieties other than Standard Mandarin used for broadcasting by China Radio International, alongside Cantonese, Minnan, Teochew, and Hakka.
For more information see: http://en.wikipedia.org/wiki/Wenzhounese