Zambezi River vs Northern Rhodesia

Zambezi River and Northern Rhodesia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Zambezi River	Yes	No	No	No
Northern Rhodesia	Yes	No	No	No

Zambezi River (noun)	Northern Rhodesia (noun)
the fourth-longest river in Africa; flows into the Indian Ocean	a republic in central Africa; formerly controlled by Great Britain and called Northern Rhodesia until it gained independence within the commonwealth in 1964