Why can’t different nationalities always live in peace?

Traditions and customs of various nationalities have been formed over quite a long time. Some of the nationalities believed, some of them still consider themselves to be more superior over others and seeks to prove this by unleashing conflicts, the purpose of which is to seize territories and forcibly subjugate their customs and faith. Despite the age of technology and the development of a sense of openness and tolerance, many people continue to follow the belief in their superiority.