Proto-Baltic (PB, PBl, Common Baltic) is the unattested, reconstructed ancestral proto-language of all Baltic languages. It is not attested in writing, but has been partly reconstructed through the comparative method by gathering the collected data on attested Baltic and other Indo-European languages. It represents the common Baltic speech that approximately was spoken between the 3rd millennium BC and ca. 5th century BC, after which it began dividing into West and East Baltic languages.Mažiulis V. J. Baltic languages. Development of the individual Baltic languages. Encyclopedia Britannica. Proto-Baltic is thought to have been a fusional language and is associated with the Corded Ware and Trzciniec cultures.Gimbutienė, Marija (2004). Балты [Baltic people] (in Russian). Moscow: Centrpoligraf. pp. 60–74; 223. .
Generally, Proto-Baltic had a SOV word order. Proto-Baltic is said to have possessed certain unique traits, such as turning short Proto-Indo-European vowels *o, *a into *a, retaining and further developing the Proto-Indo-European ablaut, retaining *m before dental consonants, the productivity of the word stem ē and free accentuation with two pitch accents. Also, the proto-language is thought to have had its own set of diminutive suffixes, identical endings for verb tenses and moods, past tense by applying thematic vowels *-ā- and *-ē-, as well as its own lexicon, including onomastic elements.
Proto-Baltic area
Baltic hydronyms cover a vast area of 860,000 km2 from Vystula River in the west to Moscow in the east and from the Baltic Sea in the north all the way to Kyiv in the south. The current Lithuanian and Latvian lands combined constitute approximately one-sixth of the former Baltic territory.Zinkevičius, Zigmas (1984). Lietuvių kalbos istorija [History of Lithuanian] (in Lithuanian). I. Vilnius: Mokslas. p. 151. . Some researchers suggest that in the past Baltic lands from Vystula to Daugava were inhabited by Baltic Finnic tribes but they were assimilated by the Baltic newcomers later on.Smoczyński, W. (1986). Języki indoeuropejskie. Języki bałtyckie [Indo-European languages. Baltic languages] (in Polish). Warsaw: PWN.Zinkevičius, Zigmas. (1984). Lietuvių kalbos istorija [History of Lithuanian] (in Lithuanian). I. Vilnius: Mokslas [Science]. pp. 154–155. . There is still an ongoing debate regarding the boundary of hydronyms in the southwest: Lithuanian linguist believed that practically all of the basins of Oder and Vystula Rivers belonged to the Baltic hydronym habitatKaraliūnas S. (2005). Baltų praeitis istoriniuose šaltiniuose. 2. [The Past of the Balts in Historical Records. 2.] (in Lithuanian). Vilnius: Lietuvių kalbos institutas [Institute of Lithuanian language]. pp. 404–411. . while German linguist Hermann Schall suggested that Baltic hydronyms could be found much further west all the way to Elbe, Saxony and Rügen island.Zinkevičius, Zigmas. (1984). Lietuvių kalbos istorija [History of Lithuanian] (in Lithuanian). I. Vilnius: Mokslas [Science]. p. 150. . During the 2nd and 1st millennium BC, the Baltic people inhabited larger territories than Germanic and Slavic people did at the time.Zinkevičius, Zigmas. (1984). Lietuvių kalbos istorija [History of Lithuanian] (in Lithuanian). I. Vilnius: Mokslas. p. 151. . It is estimated that the Proto-Baltic lands had up to 500,000 people.
Inhabitants of the Proto-Baltic area were surrounded by Germanic people in the west, Slavs in the south and Finno-Ugric people in the north and northeast. Russian philologist Vladimir Toporov believes that during 1000–800 BC Proto-Germanic people began expanding into the western Baltic territory starting from the Pasłęka River. Later on, the Baltic area began shrinking even more due to the migration of the Goths. During the migration period Slavic people began expanding into the northern and eastern territories of the Balts. From 11th to 12th century, Russian scriptures mention ongoing battles near Moscow with Eastern Galindians.Zinkevičius, Z. (1984). Lietuvių kalbos istorija. I. [History of Lithuanian Language, 1st edition] (in Lithuanian). Vilnius: Mokslas. p. 248. . Since 1225, the conquests of the Teutonic Order in the current Baltic region intensified and later on resulted in the extinction of the Old Prussian speakers in the 18th century.Mallory, P.; Douglas, Q. Adams (1997). Encyclopedia of Indo-European culture. London: Fitzroy Dearborn Publishers. pp. 497. .
Relationship with other language groups
Slavic languages
After a long-running debate in the 20th century about the exact nature of the relationship between the Baltic and Slavic branches of the Indo-European family, in the 21st century many historical linguists moved firmly in favour of a shared genealogical history between these two branches, both deriving from a common intermediate source, Proto-Balto-Slavic, after the breakup of Proto-Indo-European.Pronk, Tijmen (2022). "Balto-Slavic". In T. Olander (ed.). The Indo-European Language Family: A Phylogenetic Perspective. Cambridge University Press. p. 269. "During the last quarter of a century, the communis opinio appears to have moved firmly in favour of the idea that there was indeed a period of shared innovations between Baltic and Slavic directly following the disintegration of the Proto-Indo-European parent language." Those in opposition continue to be sceptical about the nature of such a relationshipPetit, Daniel (2004). Les langues baltiques et la question balto-slave [The Baltic Languages and the Balto-Slavic Question] (in French). Paris: École normale supérieure. pp. 34–35. "Currently, few scholars still defend the idea of a single Balto-Slavic language [...] If Balto-Slavic existed, it was surely not as a totally unified language, but rather as a group of dialects permeable to the diffusion of isoglosses." and are uncertain whether it is even ascertainable.Schmalsieg, R. William (2013). Review of Aisčiai. Kilmė [The Aistians: Their Origin], by Eugenijus Jovaiša. Acta Linguistica Lithuanica. p. 152. "I personally think the Balto-Slavic problem is insoluble, since whatever common changes the Baltic and Slavic may have could just as well be ascribed to parallel development." While Balto-Slavic has been traditionally divided into two main branches, viz. Baltic and Slavic, some linguists like Frederik Kortlandt or Rick Derksen proposed that Proto-Balto-Slavic split into three language groups — East Baltic, West Baltic and Proto-Slavic — without a Proto-Baltic stage, which is a view opposed by Miguel Villanueva SvenssonSvensson, Miguel Villanueva (2014). "On the relationship between West Baltic and East Baltic". In Tatyana Tsivyan, Artūras Judžentis, Maria Zavyalova (Eds.), Baltai ir slavai: Dvasinių kultūrų sankirtos [Balts and Slavs: The Intersection of Spiritual Cultures]. Vilnius: Versmė. p. 172. "The development of the verbal system, I believe, strongly supports the traditional notion that Old Prussian, Lithuanian and Latvian are to be derived from a common unitary Proto-Baltic […] This conclusion is clearly supported by the lexicon." and Eugen Hill.Hill, Eugen (2016). "Phonological evidence for a Proto-Baltic stage in the evolution of East and West Baltic". In (Eds.), International Journal of Diachronic Linguistics and Linguistic Reconstruction. p. 227. "The traditional assumption of a Proto-Baltic stage in the development of Baltic languages can be additionally supported by two non-trivial phonological developments found both in East and West Baltic but not shared by Slavonic. The first development is the shortening of Proto-BSl *ī̃ in unstressed syllables. The second development is the characteristic contraction of the vowels in Proto-BSl *-iā- into something like *-ē̃-, whereas no contraction occurred in Proto-BSl *-ii̯ā-." Historical linguist Brian D. Joseph argues that in the context of other Indo-European phylogenetic clades, the qualitative evidence for Balto-Slavic is not on par with Indo-Iranian, insofar as Balto-Slavic lacks evidence for shared culture (as is also the case for Italo-Celtic).Joseph, Brian D. (2017). Balto-Slavic: what Meillet was Thinking, or, what was Meillet Thinking?! The Ohio State University. pp. 44–45. Other scholars point out that the phonology and morphology, which is shared by all known Baltic languages, is much more archaic than that of Proto-Slavic, retaining many features attributed to other attested Indo-European languages roughly 3000 years ago.
It is also known that some Baltic and Slavic languages have more in common than others: Old Prussian and Latvian share more commonalities with Slavic languages than Lithuanian does. Some similarities between Baltic and Slavic can be found on all levels of linguistic analysis, which led German philologist August Schleicher to believe that there was indeed a common point of development. French linguist Antoine Meillet, however, rejected this idea and claimed that similarities between Baltic and Slavic languages were a result of close contact. Meanwhile, Latvian linguist Jānis Endzelīns suggested that following the split of PIE, Baltic and Slavic languages evolved independently, but later experienced a common period of greater contact. Jan Michał Rozwadowski proposed that the two language groups were indeed a unity after the division of Indo-European, but also suggested that after the two had divided into separate entities (Baltic and Slavic), they had posterior contact. Russian linguists Vladimir Toporov and Vyacheslav Ivanov believed that Proto-Slavic language formed from the peripheral-type Baltic dialects. Thus, there are at least six points of view on the relationships between the Baltic and Slavic languages.
Germanic languages There is some vocabulary (about 60 words) that Baltic and Germanic languages share, excluding loanwords. Common vocabulary mostly includes words relating to work, equipment, agriculture etc., such as Proto-Baltic *darbas, meaning 'work' and Proto-Germanic *derbaz, meaning 'bold, determined, strong' < *derbaną 'to work', Proto-Baltic *derṷā and Proto-Germanic *terwą, meaning 'tar, resin', Proto-Baltic *gāmurii̯as and Proto-Germanic *gōmô, meaning 'palate'. Baltic and Germanic languages also share numeral formation for 11 to 19, both partially possess the same formation of verbs in past tense (ablaut), absence of the aorist. According to German linguist , at first Proto-Baltic was a centum language along with Proto-Germanic, but it eventually became satem later on. Some scholars believe that Baltic and Germanic contacts are older than those with Slavic languages while others claim the opposite. According to Lithuanian linguist , Germanic people borrowed certain suffixes from their Baltic neighbours, such as *-ing-, *-isko-, *-ō-men- (e.g. Old High German: arming 'poor person', Old Icelandic: bernska 'childhood', Gothic: aldōmin () 'senility'). Both Baltic and Germanic emotional verbs possess similar semantic development, which is evinced by roots like *dhers- and *dreǵh-. This semantic group is also noted for having exclusive isoglosses (e.g. PIE: *dreǵh-, *dherbh-, *u̯rengh-, *peḱ-), though they differ in meaning.Jurkutaitytė, Rita (2001). Emocijų veiksmažodžiai baltų ir germanų kalbose [The Emotional Verbs in Baltic and Germanic Languages] (in Lithuanian, abstract available in English and German). Klaipėda University. p. 75.