Learn English – “I must to England” in Hamlet: What does “must” mean without an infinitive

Constructions using the equivalent of "do" as an auxiliary for reasons of emphasis or particular meanings are known in other languages.

An example that comes to mind is Middle Welsh: In the Mabinogion, for example the phrase "oruc ... a" occurs often before another verb, and means "did and ..." or "made and ...".

It is also theorised that the "-d/t" ending of weak Germanic past tenses (eg "walked") is a remnant of an ancestor of "did", so "walked" comes originally from the collocation "walk did" (not in English but in an ancestor language).

In modern standard English we use "do" in the affirmative only for emphasis or ("I do want it"), but in some dialects, and in older forms (eg Shakespeare), it is more common. In fact in Shakespeare, we find both affirmative and negative sentences with and without "do".

I have a theory about why "do" has spread to be compulsory in the negative in modern English: I think that Jespersen's Cycle operated to create an anomalous Head-modifier construction ("I go not", where the "not" follows the head word "go"), and the modern form has spread because it is more normal in English constructions for the modifier to precede the head ("I don't go"). I've not seen this idea suggested anywhere else, though the application of Jespersen's Cycle to Old English is well established.

The verb I would use is regionalize. This would not refer to a "paper" partitioning, but rather dividing a country on a map for the purposes of say, marketing.