Korea as a whole was a nation for over two thousand years; 99% of the population on the peninsula is of Korean ethnicity. After the war, citizens of South Kore

Korea as a whole was a nation for over two thousand years; 99% of the population on the peninsula is of Korean ethnicity. After the war, citizens of South Korea volunteered, for no pay, to rebuild infrastructure (roads, factories). From the 60s through the 80s, there was one singular goal, namely, building the nation and becoming a prosperous society. I think that kind of scenario is a little harder to reproduce in the more heterogenous parts of the world. How do you propose getting opposing ethnicities in other countries to pull together like that?