I am referring to the figure below, obtained from Wikipedia
I am aware that about 40% of all Chinese can be characterised into 10 or so surnames. However, breaking it down, there are particular surnames that are common in certain provinces.
I was wondering if anyone knows the history behind this geographic distribution?
I know that certain surnames, such as 陳 were named after their vassal states of China (pre warring state). But obviously, the geography has changed significantly since then.
Are there any other reasons for the high concentration below?