I always thought the reason for it was necessity. The African tribes, for example, needed only shade from the sun, water and food. The land isn't much good for farming, and animals would tend to stick around water, till it dries up. So a nomadic existence is in order, there's no need to settle, since a settlement would last only as long as the water source.
Whereas in 'white' countries, the colder weather means finding permanent shelter is more practical, and the permanent water sources make long-term civilisation easily viable. It's not that white races were the only ones to rape, pillage and conquer. It was just that when two desert tribes clashed, all that was at stake was the people in the tribe and whatever small possessions they had. The permanence of European communities and such meant more was fielded, more was gained, and more communities learned the benefit of co-operation, eventually forming the nations we know today. So then the Western civilisations created through necessity and centuries of escalating war, met the cultures that had fought their wars in a constant stalemate.
Whereas in 'white' countries, the colder weather means finding permanent shelter is more practical, and the permanent water sources make long-term civilisation easily viable. It's not that white races were the only ones to rape, pillage and conquer. It was just that when two desert tribes clashed, all that was at stake was the people in the tribe and whatever small possessions they had. The permanence of European communities and such meant more was fielded, more was gained, and more communities learned the benefit of co-operation, eventually forming the nations we know today. So then the Western civilisations created through necessity and centuries of escalating war, met the cultures that had fought their wars in a constant stalemate.