[barry-cotter]

Heilongjiang is part of the Northeast, aka former Manchuria and was settled in the mid to late 1800s from the North Chinese plain. The entire North Chinese plain speaks variants of Mandarin for the same reason North American English is far less diverse than British and Irish English, there was a relatively small recent founder population.

Wu (Shanghainese and the other related dialects of the Yangtze river delta), Yue (Cantonese), Hakka, Xiang and Min are absolutely languages. They're at least as divergent as the Romance languages or the different "dialects" of Arabic. Having a single written standard does not make the spoken varieties one language. And even if it did Cantonese has a written standard even if it's not used much, so there are at least two Chinese languages.

https://en.wikipedia.org/wiki/List_of_varieties_of_Chinese https://en.wikipedia.org/wiki/Written_Cantonese

[tonylinn80]

I speak a branch of Wu myself, and it's ABSOLUTELY not a different language from other dialects of Chinese. There are small parts (also commonly used) of the dialects that's dramatically different from Mandarin, but most parts are still the same. Especially if you need to speak about things in a more formal context, or describe concepts that are more abstract, the dialects has no difference with each other if written down

[jacobolus]

The pronunciation of words in Wu Chinese and Mandarin is systematically different, and many common words are entirely unrelated. Typical Mandarin speakers can’t understand Wu Chinese at all.

The relationship is similar to that between English and German or French and Italian.