Australian Aborigines, Red Indians, Sri Lankan Veddas, Japanese Ainu, Kung Bushmen of Africa, Mayans of Mexico… etc were some of the dominant inhabitants of the Earth before the establishment of the modern man. They are culturally different among themselves, and the geographical boundaries viz. oceans have been the main extrications.
Modern man is vastly different culturally among continents as well as among countries. In addition, these cultural differences could extend even more within a country. With the globalization takes place, those cultural differences will become narrower. Physical barriers within modern men could not restrict them to isolate from others as the technologies arose to travel and transport