American political scientist Samuel P. Huntington considered the Sinic world as one of many civilizations in his book "The Clash of Civilizations". He notes that "all scholars recognize the existence of either a single distinct Chinese civilization dating back to at least 1500 B.C. and perhaps a thousand years earlier, or of two Chinese civilizations one succeeding the other in the early centuries of the Christian epoch." Huntington's Sinic civilization includes China, North Korea, South Korea, Mongolia, Vietnam and Chinese communities in Southeast Asia. Of the many civilizations that Huntington discusses, the Sinic world is the only one that is based on a cultural, rather than religious, identity. Huntington's theory was that in a post-Cold War world, humanity "with cultural groups: tribes, ethnic groups, religious communities [and at the broadest level, civilizations."