Just some background for my question.
In China they have a lot of dialects, with Mandarin as the unifying language (it was based on the Beijing dialect) in 1911. Some of these Chinese have migrated overseas within the last 100-200 years ago or even longer.
I was just thinking of a word to describe a language used by only a particular group of people who share the same ancestral dialect (in a foreign country), as in the sentence:
"There's no point in learning such a/an _______ language".
This adjective is to say that the language is not used by many people and only limited to this specific group. By the way, these dialects are not dying languages (or dialects - I like to think of them as languages)
Is exclusive the right word here? If so, are there any other words that can be used in this context?