chain of mountains vs Black Hills

chain of mountains and Black Hills both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain of mountains	Yes	No	No	No
Black Hills	Yes	No	No	No

chain of mountains (noun)	Black Hills (noun)
a series of hills or mountains	mountains in southwestern South Dakota and northeastern Wyoming; sacred to the Sioux (whites settling in the Black Hills led to the Battle of Little Bighorn); site of Mount Rushmore