Unfortunately, the current 'standard' grouping of Min languages is all wrong. Actually, Min languages can be grouped into only 3 distinct grouping i.e. Southern Min, Northern Min and Eastern Min.
1. Northern Min (Minbei, Minzhong, Shaojiang Min) - Both Shaojiang Min and Minzhong split off from Minbei around a few hundred years ago.They are all mutually unintelligible.
2. Eastern Min (Mindong, Manhua?, Manjiang?) - there are actually a few mutually unintelligible languages that split off from Mindong.
3. Southern Min (mentioned in thread below)
http://www.chinalanguage.com/forums/vie ... 62d93df325
The historical establishment of Fuzhou city (Eastern Min) is quite different from the historical establishment of Quanzhou city (Southern Min) i.e. Quanzhou language didn't split off from Fuzhou language.
I somewhat (but not entirely) agree with the author of the link below. If we base languages on mutual intelligibility, there are at least a few thousand Chinese languages in China and not just 7 in the 'standard' classification.
https://robertlindsay.wordpress.com/200 ... ification/