The Swadesh wordlists for a variety of Zhuang-Tai idioms. Most of the data are taken from field records collected under the supervision of Ilya Peiros in 2000-2003 for the Intercontinental Dictionary Series Project (IDS), which explains the large number of idioms marked mostly for their geographical location rather than according to any "standard" scheme of Zhuang-Tai classification.
The wordlists are linked to the Zhuang-Tai etymological database; however, since the latter is currently based on older publications on Tai historical linguistics, not specifically connected with the IDS project, it should be noted that there are some discrepancies between the two databases. Namely, they obviously do not agree as to the number of languages involved, and also, for many of the items found in the wordlists no etymologies are available, even though many of them most certainly reflect older Proto-Zhuang-Tai roots, because these etymologies were not found in the sources used. A more proper coordination between the wordlists and the etymologies is, then, an important task for future research.
Results of lexicostatistical calculations, reflected in the tree diagram available on the site, show that the traditional tripartite division of Zhuang-Tai languages into Shan-Tai ('Southwestern'), Nung ('Central'), and Zhuang ('Northern') branches is accurate, with one important modification: Nung and Zhuang languages are inarguably closer to each other than to the Shan-Tai branch, which means that an intermediate "Nung-Zhuang" stage has to be set up as well. However, within each particular branch, the languages are so closely related that proper classificatory schemes often depend on a matter of one or two extra percent of correlations, meaning that on such levels lexicostatistical results are not highly reliable.