first scientific fieldwork description of Chuvash, by August Ahlqvist in 1856, allowed researchers to establish its proper affiliation. Chuvash language is a highly divergent form of Turkic, and is not easily recognized as such. Some scholars suggest Hunnic had strong ties with Chuvash and classify Chuvash as Hunno-Bulgar. Chuvash is so divergent from the main body of Turkic languages that some scholars formerly considered Chuvash to be a Turkified Finno-Ugric (Uralic) language. Conversely, other scholars regard it as a Turkic language heavily influenced by Finno-Ugric languages. The following sound changes and resulting sound correspondences are typical: Most of the (non-allophonic) consonant changes listed in the table above are thought to date from the period before the Bulgars migrated to the Volga region in the 10th century; some notable exceptions are the č > ś shift and the final stage of the -d > -ð > -z > -r shift, which date from the following, Volga Bulgar period (between the 10th-century migration and the Mongol invasions of the 13th century). The vowel changes mostly occurred later, mainly during the Middle Chuvash period (between the invasions and the 17th century), except for the diphthongisation, which took place during the Volga Bulgar period. Many sound changes known from Chuvash can be observed in Turkic loanwords into Hungarian (from the pre-migration period) and in Volga Bulgar epitaphs or loanwords into languages of the Volga region (from the Volga Bulgar period). Nevertheless, these sources also indicate that there was significant dialectal variation within the Oguric-speaking population during both of these periods. Comparison with Turkic languages In the VIII—X centuries in Central Asia, the ancient Turkic script (the Orkhon-Yenisei runic script) was used for writing in Turkic languages. Turkic epitaphs of VII-IX AD were left by speakers of various dialects (table): Often in the Chuvash language, the Turkic sounds -j- (oguz), -d- (uighur), -z- (kipchak) are replaced by -r- (oghur), example rotacism: Words in the Turkic languages: leg, put- j - language (Oguz): ajaq, qoj- d - language (Uyghur): adaq, qod- z - language (Kypchak): azaq, qoz- r - language (Oghur): urah, hor- Often in the Chuvash language, the Turkic sound -q- is replaced by -h-, example hitaism : Words in Turkic languages: black, goose, girl, zucchini Oguz, kipchaks: qara, qaz, qyz, qabaq Chuvash: hura, hur, hĕr, hupah The -h- sound disappears if it is the last letter . Dudaq - Tuta - Lips instead of