Why are numeral classifiers required in White Hmong noun phrases?

In White Hmong, numeral classifiers are required in noun phrases that contain overt numerals, as well as in phrases where the noun's reference is fixed by a demonstrative or a possessive pronoun.1

Because Hmong-Mien languages lack grammatical markers for number or case on nouns, these languages rely heavily on syntax and discourse structures to organize meaning. The classifier serves a functional role by indicating the category to which a noun belongs—such as animate objects—or by designating specific measurable quantities and countable items. By using these classifiers, speakers can clearly define the reference of a noun within a phrase, compensating for the absence of internal word-level grammatical structure.1