[grotesqueness]

Not true, Southern China was home of varies of Yue people before First Emperor sent Han troops from northern China conquer them, there were hundred of tribes of Yue. So called 百越。Nan Yue occupied Northern Vietnam, Guangdong and Guangxi. Min Yue covered Fujian. There are also Zhejiang and Jiangsu people who were also part of Yue but spoke entirely different dialect from Cantonese. There is also Gan Yue, people live in Jiangxi and Hunan.

olden cantonese was already spoken and spread over southern china by then

the biggest problem is modern cantonese and olden cantonese have lot of differences