Ethnic cleansing is where two or more different people commit violence because of resources or religious differences. the latter can be dealt with or mediated by missionaries, but the first case will be harder to sort out. Let's start with resource scarcity? when two families fight for the goods, that is for them - they need it. if two tribes fight for it, they are made of families. to suggest they share is positively stupid, as then there will be two sides without enough, so, i am suggesting they receive seeds and fertilizer from charity, a one dollar donation from a handful of people will be enough for the seeds, of course. then, there will be plenty for everyone. Then, the cultural differences do not affect each other. if missionaries from churches in the cities of those countries or regions that they are in go out to them, for a holiday or a reference for work one day, then they will bring all sorts of ideas to the region.