The World around "Us"

Does "us" literally refer to only us or does it include "them" as well? I think these distinctions are rather useless. People complain about globalization and its ills, claiming that the growing trend is killing off local heritage and individuality. However, why should cultural diversity be celebrated when in its defense we can only gain enmity and suspicion from "them"? To a fair extent, cultural diversity and hence a "clash of civilizations" has led to genocide, terrorist attacks and civil wars, amongst other calamities plaguing the world of today. Look at the fight between "us" and the terrorists. Or the Darfur conflict in Sudan. Or the massacres in the former Yugoslav states and Rwanda. Or the more recent case in which the Chinese have reacted strongly against the West regarding issues pertaining to Tibet and the Olympics. Cultural diversity is a worthy price to pay in order to make the world a more coherent and homogeneous one to live in. Let there be no demarcation between "us" and "them". We are all global citizens, everyone a part of the human race.