Different groups of people get along because we're all still human and very similarly culturally and understand each other's desires and goals. Things start goi

Different groups of people get along because we're all still human and very similarly culturally and understand each other's desires and goals. Things start going badly when there's major social and technological differences. Think of how things went for the natives when America was discovered. Now amplify it. Imagine if different countries were isolated from each other for millions of years, evolving into different species, and advancing technology the whole time, lost track of any commonalities between each other, and were then exposed to each other.