[USFRIENDINVICTORIA]

You could also say uni-cultural society, vs. multicultural society. Less identity politics.

[Jack Black]

You could also say uni-cultural society, vs. multicultural society. Less identity politics.

You could. The existing term is "ethnostate". Japan is an ethnostate, meaning it is made up of people exclusively (or overwhelmingly) of one ethnic background: Japanese.

There are still many ethnostates in the world, but they are shrinking. Poland and Iceland come to mind.