Ratliff (2021) estimates that the split between Hmongic and Mienic had occurred before 2500 BP, since the Old Chinese words 鐵 tiě ‘iron’ and 下 xià ‘descend’ were both borrowed separately by Proto-Hmongic and Proto-Mienic.
[1] In earlier studies, the date of proto-Hmong-Mien has been estimated to be about 2500 BP by Sagart, Blench, and Sanchez-Mazas (2004),[2] as well as by Ratliff (2021:247).
[1] It has been estimated to about 4243 BP by the Automated Similarity Judgment Program (ASJP),[3] however, ASJP is not widely accepted among historical linguists as a sufficiently rigorous method to establish or evaluate relationships between language families, since it only makes use of 40 basic vocabulary items.
[12] Even though Mienic languages usually have vowel length, Ratliff ascribes this to areal features that were borrowed after the breakup of Proto-Mienic.
Below are some words roughly belonging to the semantic domains of agriculture and subsistence from Ratliff (2004),[22] with the Proto-Hmong-Mien and Proto-Hmongic reconstructions from Ratliff (2010), and Old Chinese reconstructions from Baxter & Sagart (2014)[23] for comparison (note that the Old Chinese forms are not necessarily cognate with the Hmong–Mien forms).
In comparison, William H. Baxter and Laurent Sagart (2014)[24] reconstruct the Old Chinese name of the Mán 蠻 (Nanman 南蠻, or southern foreigners) as 蠻 *mˤro[n]; additionally, Sidwell & Rau (2015) reconstruct the Proto-Austroasiatic word for 'person' as *mraʔ.
[25] Proto-Hmong–Mien shares many lexical similarities with neighboring language families, including Austroasiatic, Kra-Dai (Tai-Kadai), Austronesian, and Tibeto-Burman (Ratliff 2010).
Many lexical resemblances are found between the Hmong-Mien and Austroasiatic language families (Ratliff 2010), some of which had earlier been proposed by Haudricourt (1951).
[33] Many lexical resemblances are found between the Hmong-Mien and Kra-Dai language families, although the tones often do not correspond (Ratliff 2010).
Many lexical resemblances are found between the Hmong-Mien and Austronesian language families, some of which are also shared with Kra-Dai and Austroasiatic (Ratliff 2010).
Guillaume Jacques (2021) notes that there are Tibeto-Burman parallels for various Hmong-Mien words that are found specifically in rGyalrongic and neighboring Qiangic languages.