Are you the guy that goes around on Youtube, saying "Asia for the Asians, Africa for the Africans, but America is being condemned to white genocide...bla...bla...bla"?
Because I don't think you've taken so much as a brief gander at the history of those lands.
Africa is probably one of the most diverse continents around, dude. Thousands of cultures, many with their own language. You couldn't be more wrong about that continent being a mono-culture. Take a look.
https://en.wikipedia.org/wiki/List_of_ethnic_groups_of_Africa
And India? Come on man. It's similar to Africa, in that it's got all sorts of cultures in close proximity.
https://en.wikipedia.org/wiki/South_Asian_ethnic_groups
China is a pretty huge beast, and it's pretty fucking diverse. Over 56 ethnic groups, man.
https://en.wikipedia.org/wiki/List_of_ethnic_groups_in_China
There are more Mongols living in China than there are Scots in Scotland, for crying out loud.
Hell, even the fairly isolationist Japan has quite a few foreign cultures living on that tiny place. Notably, Filipino, Brazillian and Chinese minorites are fairly entrenched.
https://en.wikipedia.org/wiki/Ethnic_groups_of_Japan
...Have you ever google'd this matter before? All I had to do was type "Country/continent" coupled with "ethnic groups" into the search bar, and voila.
Mono-culture my left buttock, lad.