Being homogenous and being suspicious of each other are different matters.
Being homogenous means sharing common things, like written language, culture, festivals, traditions, way of life, etc., etc. The mainland Chinese are definitely more homogenous than the Europeans and for USSR. Of course, they are less homogenous than the Japanese and Koreans, but Japan and Korea are small compared to China.
The Northern Chinese and Southern Chinese divide is over exaggerated.
bro, you are wrong, chinese are actually very suspicious of one another when benefits are concerned. they are just modest and do not show it.