british english - Using "them" instead of "those"

Background:

Nowadays, I see this usage a lot. I don't know if it was this common in the past.

For example: "one of them people"

When I did a research about it, some people say it comes from a dialect of British English. And some says it is a "non-standard" usage.

I see this usage in Canadian English also and seems like some people use in a sarcastic way.

Moreover, I saw in a song title as "one of them days". And I saw in the book called "A Broken Promise" as "Now my mother become one of them people."

And finally, Wikipedia says that it is a usage in Appalachian English (a common name for the Southern Midland dialect of American English):

Pronouns and demonstratives

"Them" is sometimes used in place of "those" as a demonstrative in both nominative and oblique constructions. Examples are "Them are the pants I want" and "Give me some of them crackers."

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Question(s):

What would you say about the usage of this word? Is it correct? Can we use it in daily speech? Can this usage go beyond a specific dialect and be used in other dialects, regions etc.?

Is it really originated from Appalachian English? Why did this usage become popular among other English speakers?

Note: I already saw this question:

What are the grammatical rules for use of "these", "those", and "them"?

But it only says "ungrammatical" there. This question is specific to this situation only and there is more to it.

Answer

In the succinctly named textbook: English Grammar in Familiar lectures. Embracing a new Systematick Order of Parsing. A New System of Punctuation, Exercises in false Syntax, and A System of Philosophical Grammar. Designed for the use of Schools and Private Learners by Samuel Kirkham, dated 1834 we have this example of usage pertaining to Pennsylvania

The author provides further examples and an explanation as to why this construction is considered ungrammatical

I found an even earlier instance from an American textbook illustrating this usage, dated 1803, The Elements of English Grammar: Methodically Arranged for the Assistance of Young Persons, Who Study the English language Grammatically by George Neville Ussher ¹

The above extracts prove without doubt that this form of speech (and writing) was used and heard in the past. I cannot say for certain if this usage of them originated in the Central and Southern Appalachian Mountain region of the Eastern United States. I can only testify that when I attended primary school in North London way back in the 70s this form of speech was very common among children.

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Aha! I found an even older school textbook The Rudiments of English Grammar For the Use of Those Who Have Made Some Proficiency in the Language
By Joseph Priestley, dated MDCCLXXII (1772) printed in London, England.²