Ethnic distinctions are thus akin to racial distinctions rather than linguistic or cultural ones. Thus, not all members of a nation might be members of the same ethnic group. To historians and scholars of international relations, the word state signifies a sovereign or independent government that administers a set territory. The word country is usually a synonym for state. Today we take the term nation-state for granted, because it is the standard model of territorial government today.
People tend to think that the whole world is organized that way.
It is not now, nor has the nation-state been the dominant form of territorial government throughout most of human history. One of the fundamental trends of 19th century European history was the growth of nation-states. Old multinational empires, especially in Central Europe and the Balkans, were gradually being eroded and replaced by independent countries, based on their subject nationalities. Britain, France, and Spain already had well-established countries by 1800, based on dynastic rule and the supremacy of one national group. Germany and Italy became unified, independent countries for the first time in recent history in the 1860's and 1870's.