A Nation is defined in Black's law dictionary 6th edition as “A people, or aggregation of men, existing in the form of an organized jural society, usually inhabiting a distinct portion of the earth, speaking the same language, using the same customs, possessing historic continuity, and distinguished from other like groups by their racial origin and characteristics, and generally, but not necessarily, living under the same government and sovereignty.”
Its not really honest to say that the slaves and servants of the South formed us into a Nation -- they might, you could argue anyway, formed us into a country, or an empire but certainly not into a Nation. The vast majority of the Southern slaves and servants belong either to different Nations or are just members of tribes and bands of people who don't constitute a Nation of their own. The way people throw around State, Country and Nation so appalling and misleading.