>Southern provinces in China still speak different languages (e.g. Cantonese) influenced by the indigenous languages of non-Sinitic ethnic groups.

This is interesting because I've usually heard the reverse that Mandarin varieties were influenced in pronunciation and vocabulary by non-Sinitic groups due to Mandarin being originally distributed along the northern and southwestern frontiers.

Do you have some examples of the non-Sinitic influence on southern families of Chinese languages? I'm particularly interested what influences are on Min since it is considered to have developed separately from Old Chinese unlike Mandarin, Yue, or Wu which are considered to descend from Middle.