Classifiers before numerals Origin of an atypical morpheme order

Languages with sortal classifiers (CLF) are distributed across the world, with a large concentration in East and South (east) Asia. Across the world's classifier languages, few are attested which order classifiers before numerals in counted noun phrases (CLF NUM). The Sino-Tibetan language family includes languages without sortal classifiers, languages with the more typical NUM CLF order, as well as languages with CLF NUM order. The latter group of languages are concentrated in Northeast India and neighboring regions. The Sino-Tibetan languages with CLF NUM order do not fit under one genealogical node. The present hypothesis is that the classifiers arose through repetition of the counted noun, following which the order spread via contact. The CLF NUM order appears to have arisen at least as early as the time of Proto-Bodo-Garo. However, we do not yet find cognate classifiers at a time depth beyond Proto-Bodo-Garo. A remaining mystery is why such a cross-linguistically rare morpheme order spread so easily within the Northeast India linguistic area.