Mainstream scholarship places Bulgar among the "Lir" branch of Turkic languages referred to as Oghur Turkic, Lir-Turkic or, indeed, "Bulgar Turkic", as opposed to the "Shaz"-type of Common Turkic. The "Lir" branch is characterized by sound correspondences such as Oghuric /r/ versus Common Turkic (or Shaz-Turkic) /z/ and Oghuric /l/ versus Common Turkic (Shaz-Turkic) /š/. As was stated by Al-Istakhri, "The language of the Khazars is different than the language of the Turks and the Persians, nor does a tongue of (any) group of humanity have anything in common with it and the language of the Bulgars is like the language of the Khazars, but the Burtas have another language." The only surviving language from this linguistic group is believed to be Chuvash. Omeljan Pritsak in his study "The Hunnic Language of the Attila Clan" (1982) concluded that the language of the Bulgars was from the family of the Hunnic languages, as he calls the Oghur languages. According to the Bulgarian Antoaneta Granberg, "The Hunno-Bulgar language was formed on the northern and western borders of China in the 3rd-5th c. BC." The analysis of the loan-words in Slavonic language shows the presence of direct influences of various language-families: Turkic, Mongolic, Chinese and Iranian.
The language of the Danube Bulgars (or Danubian Bulgar) is recorded in a small number of inscriptions, which are found in Pliska, the first capital of First Bulgarian Empire, and in the rock churches near the village of Murfatlar, in present-day Romania. Some of these inscriptions are written with the Greek characters, others with the Kuban alphabet which is similar to the Orkhon script. Most of these appear to have been of a private character (oaths, dedications, inscriptions on grave stones) and some were court inventories. Although attempts at decipherment have been made, none of them has gained wide acceptance. These inscriptions in Danubian Bulgar are found along with other, official ones written in Greek; which was used as the official state language of the First Bulgarian Empire until the 9th century, when it was replaced by Old Bulgarian (Slavonic).
The language of the Danubian Bulgars is also known from a small number of loanwords in the Old Bulgarian language, as well as terms occurring in Bulgar Greek-language inscriptions, contemporary Byzantine texts, and later Slavonic Old Bulgarian texts. Most of these words designate titles and other concepts concerning the affairs of state, including the official 12-year cyclic calendar (as used in the Nominalia of the Bulgarian khans). The language became extinct in Danubian Bulgaria in the 9th century as the Bulgar nobility became gradually Slavicized after the Old Bulgarian tongue was declared as official in 893.
The language spoken by the population of Volga Bulgaria is known as Volga-Bulgar. There are a number of surviving inscriptions in Volga-Bulgar, some of which are written with Arabic letters, alongside the continuing use of Orkhon script. These are all largely decipherable. That language persisted until the 13th or the 14th century. In that region, it may have ultimately given rise to the Chuvash language, which is most closely related to it and which is classified as the only surviving member of a separate "Oghur-Turkic" (or Lir-Turkic) branch of the Turkic languages, to which Bulgar is also considered to have belonged (see above). Still, the precise position of Chuvash within the Oghur family of languages is a matter of dispute among linguists. Since the comparative material attributable to the extinct members of Oghuric (Khazar and Bulgar) is scant, little is known about any precise interrelation of these languages and it is a matter of dispute whether Chuvash, the only "Lir"-type language with sufficient extant linguistic material, might be the daughter language of any of these or just a sister branch.
^Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2017). "Bolgarian". Glottolog 3.0. Jena, Germany: Max Planck Institute for the Science of Human History.
^ abcEncyclopædia Britannica Online - Bolgar Turkic Archived 2008-06-23 at the Wayback Machine
^ abCampbell, George L. Compendium of the World's Languages. Routledge, 2000. page 274
^ abMarcantonio, Angela. The Uralic Language Family: Facts, Myths and Statistics. Blackwell Publishing Limited, 2002. page 25
^Marcantonio, Angela (2002). The Uralic language family: facts, myths and statistics. Wiley-Blackwell. p. 167. ISBN 0-631-23170-6.
^Price, Glanville (2000). Encyclopedia of the languages of Europe. Wiley-Blackwell. p. 88. ISBN 0-631-22039-9.
^Clauson, Gerard (2002). Studies in Turkic and Mongolic linguistics. Taylor & Francis. p. 38. ISBN 0-415-29772-9.
^ abJohanson, Lars. 1998. "The history of Turkic." In: Johanson, Lars & Éva Agnes Csató (ed.). 1998. The Turkic languages. London: Routledge, pp. 81-125."Archived copy". Archived from the original on 2011-04-08. Retrieved 2007-09-05.CS1 maint: archived copy as title (link); Johanson, Lars. 2007. Chuvash. Encyclopedia of Language and Linguistics. Oxford: Elsevier.
^Al-Istakhri translation by Zahoder B. N. "Caspian code of the information about Eastern Europe. Gorgan and Volga area in 9-11 cc", Oriental Literature, Moscow, 1962, p. 238
^"Archived copy" (PDF). Archived (PDF) from the original on 2016-12-13. Retrieved 2017-01-02.CS1 maint: archived copy as title (link)
^The Turks: Early ages, Vol. 1 , Cem Oğuz, ISBN 9756782552, Autor Murat Ocak, Redactors: Hasan Celāl Güzel, Cem Oğuz, Osman Karatay, Publisher: Yeni Türkiye, 2002, p. 535.
^The Hunno-Bulgar language, Antoaneta Granberg, "Archived copy" (PDF). Archived from the original (PDF) on 2015-11-20. Retrieved 2015-11-20.CS1 maint: archived copy as title (link)
^Granberg, Antoaneta. "Classification of the Hunno-Bulgarian Loan-Words in Slavonic". Swedish Contributions to the Fourteenth International Congress of Slavists. Archived from the original on 6 December 2015. Retrieved 26 April 2018.
^"Old Bulgar words from VI-X c. AD sources". www.kroraina.com. Archived from the original on 30 June 2017. Retrieved 26 April 2018.
^Бакалов, Георги. Малко известни факти от историята на древните българи Част 1 Archived 2015-09-24 at the Wayback Machineчаст 2 Archived 2007-12-01 at the Wayback Machine
^Димитров, Божидар, 2005. 12 мита в българската история
^Милчева, Христина. Българите са с древно-ирански произход. Научна конференция "Средновековна Рус, Волжка България и северното Черноморие в контекста на руските източни връзки", Казан, Русия, 15.10.2007
^Detrez has specialisized Bulgarian philology at Sofia University and is author of several books treating Bulgarian history Archived 2013-10-02 at the Wayback Machine.
^Detrez, Raymond; Plas, Pieter; Lang, Peter (2005). Developing cultural identity in the Balkans: convergence vs divergence. p. 29. ISBN 90-5201-297-0.
^Бешевлиев, Веселин. Ирански елементи у първобългарите. Античное Общество, Труды Конференции по изучению проблем античности, стр. 237-247, Издательство "Наука", Москва 1967, АН СССР, Отделение Истории.
^Йорданов, Стефан. Славяни, тюрки и индо-иранци в ранното средновековие: езикови проблеми на българския етногенезис. В: Българистични проучвания. 8. Актуални проблеми на българистиката и славистиката. Седма международна научна сесия. Велико Търново, 22-23 август 2001 г. Велико Търново, 2002, 275-295.
^Съпоставително езикознание, Том 30, Софийски университет "Климент Охридски", 2005, стр. 66-68.
^Исторически преглед, Том 62, Броеве 3–4, Bŭlgarsko istorichesko druzhestvo, Institut za istoria (Bŭlgarska akademia na naukite) 2006, стр. 14.
^Palaeobulgarica: Starobŭlgaristika, Том 24, Tsentŭr za bŭlgaristika (Bŭlgarska akademiia na naukite), 2000, стр. 53.
^"Образуване на българската народност. Димитър Ангелов (Издателство Наука и изкуство, "Векове", София, 1971) стр. 117". kroraina.com. Archived from the original on 28 May 2013. Retrieved 26 April 2018.
^"Образуване на българската държава, Петър Петров (Издателство Наука и изкуство, София, 1981) стр. 94". kroraina.com. Archived from the original on 12 February 2012. Retrieved 26 April 2018.
^Karloukovski, Vassil. "V. Zlatarski - Istorija 1A - a 1". www.kroraina.com. Archived from the original on 26 July 2013. Retrieved 26 April 2018.
^"Медното гумно на прабългарите, Ivan Benedikov, (College "Thrace" publishing house, I edition 1983, II. reworked edition, Stara Zagora 1995, pp. 16-19". kroraina.com. Archived from the original on 20 June 2012. Retrieved 26 April 2018.
^Curta, Florin; Kovalev, Roman (2008). The Other Europe in the Middle Ages: Avars, Bulgars, Khazars and Cumans. Brill. p. 189. ISBN 978-9004163898.
^Clark, Larry. 1998. "Chuvash." In: Johanson, Lars & Éva Agnes Csató (ed.). 1998. The Turkic languages. London: Routledge, p.434
^Формирование болгарской (древнечувашской) народности - web page
Look up Bulgar in Wiktionary, the free dictionary.
For a list of words relating to Bulgar language, see the Bulgar language category of words in Wiktionary, the free dictionary.
Britannica Online - The article describes the position of Bulgar and Chuvash in the classification of the Turkic languages.
"Sergei Starostin's Tower of Babel" (PDF). - A Russian Turkologist's take on Danube Bulgar inscriptions and the Bulgar calendar, in Russian. The article contains a tentative decipherment of inscriptions based on the Turkic hypothesis. (350 KiB)
Rashev, Rasho. 1992. On the origin of the Proto-Bulgarians. p. 23-33 in: Studia protobulgarica et mediaevalia europensia. In honour of Prof. V. Beshevliev, Veliko Tarnovo - A Bulgarian archeologist's proposal. The author concedes that the ruling elite of the Bulgars was Turkic-speaking as evidenced by the inscriptions etc., but stipulates that the bulk of the population was Iranian.